Year 5000-0 BC

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1600-600 BC: Enuma Anu Enlil - The knowledge basis for the first astrometeorological forecasts   

Examples of Enuma Anu Enlil tablets (see text below).


In present Irak, from about 4500 BC there were settlements on the edges of the marshes where the Tigris and the Euphrates reach the Persian Gulf. The region between these two rivers became known as Mesopotamia, and represents the area of the world's first major civilization. Much of the summary below is adopted from different sources in Wikepedia and from Rasmussen 2010, from where additional information is available.

In the Sumer region, close to the mouths of the Tigris and the Euphrates, the first Mesopotamian towns develop. Each grows up round a local temple, which acted as the centre of the region's economic activity. Unlike the other early river civilization within this region, that of Egypt (where a stable society was established along hundreds of miles of the Nile), Mesopotamia was characterized by constant warfare and a succession of shifting empires. Unlike in Egypt, towns in Mesopotamia therefore were sheltered by thick protective walls.

By the middle of the 4th millennium BC the Sumerians were firmly established in Mesopotamia, although it is still disputed when they arrived. By the third millennium BC, however, these urban centres had developed into increasingly complex societies. Irrigation and other means of exploiting food sources were being used to amass large surpluses. Huge building projects were being undertaken by rulers, and political organization was becoming ever more sophisticated. Throughout the millennium, the various city-states Kish, Uruk, Ur and Lagash vied for power and gained hegemony at various times.

Between 3500 and 3000 BC, for reasons still not well understood, the civilization of Southern Mesopotamia underwent a sudden growth and change, centred in the cities of Ur and Uruk. This development was perhaps driven by climatic change which rendered the old ways of agriculture less productive. People clustered into fewer, but larger, locations and the plough, potter's wheel and the introduction of bronze can be seen as responses to the demands of a more intensive economic life, and also as causes of increased complexity in that life. In this same period came the beginnings of writing, metrological systems and arithmetic.

The Sumerian temple priests, needing to keep accurate accounts and to pass on all their findings, are presumably the first people to develop a system of writing. The general opinion at that time was that the different celestial objects influenced on the environment on Earth. The study of this was known as ‘astrology’, and the people specializing in this were known as ‘astrologist’. Presumably the wish of passing on such knowledge in an efficient way to future generations was a driving force behind the early development of writing.

Extraordinary famous among such early written accounts are Enuma Anu Enlil (translation: In the days of the gods Anu and Enlil). Enuma Anu Enlil is a series of about 70 tablets dealing with Babylonian astrology. These accounts were found in the early 19th century by excavation in Ninive, near present day Bagdad. The bulk of the work is a substantial collection of omens, estimated to number between 6500 and 7000, which interpret a wide variety of celestial and atmospheric phenomena in terms relevant to the king and state. The tablets presumably date back to about 650 BC, but several of the omens may be as old as 1646 BC. Many of the reports found on the tablets represents ‘astrometeorological’ forecasts (Rasmussen 2010).

A majority of these reports simply list the relevant omens that best describe recent celestial events and many add brief explanatory comments concerning the interpretation of the omens for the benefit of the king, among other things addressing meteorological phenomena.

A typical report dealing with the first appearance of the moon on the first day of the month is exemplified below:

  • If the moon becomes visible on the first day: reliable speech; the land will be happy.

  • If the day reaches its normal length: a reign of long days.

  • If the moon at its appearance wears a crown: the king will reach the highest rank.

The subject matter of the Enuma Anu Enlil tablets unfold in a pattern that reveals the behaviour of the moon first, then solar phenomena, followed by other weather activities, and finally the behaviour of various stars and planets.

The first 13 tablets deal with the first appearances of the moon on various days of the month, its relation to planets and stars, and such phenomena as lunar haloes and crowns. The omens from this section, like those quoted above, are the most frequently used in the whole series of reports. This section is framed by tablet 14, which details a basic mathematical scheme for predicting the visibility of the moon.

Tablets 15 to 22 are dedicated to lunar eclipses. It uses many forms of encoding, such as the date, watches of the night and quadrants of the moon, to predict which regions and cities the eclipse was believed to affect.

Tablets 23 to 29 deal with the appearances of the sun, its colour, markings and its relation to cloudbanks and storm clouds when it rises. Solar eclipses are explored in tablets 30 to 39.

Tablets 40 to 49 concern weather phenomena and earthquakes, special attention being devoted to the occurrence of thunder.

The final 20 tablets are dedicated to the stars and planets. These tablets in particular use a form of encoding in which the names of the planets are replaced by the names of fixed stars and constellations.

Based on the omens in Enuma Anu Enlil the priests made forecasts for the kings. An example of this may be cited (Rasmussen 2010): “In the month Ajjaru, day 2, Venus disappeared to the west. It remained hidden on the sky in 18 days, and in the month Ajjaru, day 20, Venus reappeared to the east. There will come rain and floods to the benefit for the country.

Very often especially the Moon had high importance for these early meteorological or environmental forecasts as exemplified here (Rasmussen 2010): “When a dark halo surrounds the Moon, it will gather clouds and the month will bring rain. When the ‘horns’ of the Moon become blurred, floods will follow”.


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1400-500 BC:  Greek mythology, ancient philosophy and the wind   

Homer (left), author of the Iliad and the Odyssey, and Aeolus (right), ruler of the winds.


In the Western classical tradition Homer is the author of the Iliad and the Odyssey, and is honoured as the greatest ancient Greek epic poet. For modern scholars "the date of Homer" refers not to an individual, but to the period when the epics were created. The consensus is that "the Iliad and the Odyssey date from around the 8th century BC, the Iliad being composed before the Odyssey, perhaps by some decades. Much of the summary below is adopted from different sources in Wikepedia and from Rasmussen 2010, from where additional information is available.

When Homer lived is more controversial. Herodotus estimates that Homer lived 400 years before Herodotus' own time, which would place him at around 850 BC; while other ancient sources claim that he lived much nearer to the supposed time of the Trojan War, in the early 12th Century BC. In several of Homer’s work reference to meteorological events and interpretations can be found (Rasmussen 2010).

The Trojan War was followed by a period of about 300-400 years with few archaeological traces, until the Greek city states emerged. In modern historiography "polis" is normally used to indicate these ancient Greek city-states, which was characterized by self-governance, autonomy and independence. It was on this cultural background that ancient philosophy developed, later to evolve into modern natural science as we know it today.

Philosophy is the study of general and fundamental problems, such as those connected with existence, knowledge, values, reason, mind, and language. It is distinguished from other ways of addressing such problems by its critical, generally systematic approach and its reliance on rational argument. The word "philosophy" comes from the Greek φιλοσοφία (philosophia), which literally means "love of wisdom". Traveling sophists or "wise men" were important in Classical Greece, often earning money as teachers, whereas philosophers are "lovers of wisdom" and not professionals.

The main subjects of ancient philosophy were: understanding the fundamental causes and principles of the universe; explaining it in an economical way; the epistemological problem of reconciling the diversity and change of the natural universe, with the possibility of obtaining fixed and certain knowledge about it; questions about things that cannot be perceived by the senses, such as numbers, elements, universals and gods.

In this early period the crucial features of the philosophical method were established: a critical approach to received or established views, and the appeal to reason and argumentation. This should later evolve into modern natural science as we know it today.

The Greek city states depended on trade with associated transportation across the sea. For that practical reason the wind was considered as one of the most important meteorological phenomena in daily life (Rasmussen 2010).


The Tower of Winds below Acropolis, Athens.


According to the Greek mythology Aeolus was the ruler of the winds. In fact this name was shared by three mythic characters. Briefly, the first Aeolus was a son of Hellen and Eponymous founder of the Aeolian race; the second was a son of Poseidon, who led a colony of islands in the Tyrrhenian Sea; and the third Aeolus was a son of Hippotes who is mentioned in Homer’s Odyssey as Keeper of the Winds. Odysseus himself is famous for his his resourcefulness and the ten eventful years he took to return home after the ten-year Trojan War and his famous Trojan Horse trick. According to Homer Hippotes gives Odysseus a tightly closed bag full of the captured winds so he could sail easily home to Ithaca on the gentle West Wind. Unfortunately, while Odysseus was asleep, his crew opened the bag to inspect its contents, thereby releasing all the captured winds, and the ship was blown far away from Ithaca by a hurricane.

In ancient Greek the eight main wind directions were named and identified by different deities (see below). These are all shown on the Tower of the Winds, which is an octagonal marble tower on the Roman angora in Athens. The structure features a combination of sundials, a water clock and a wind vane. It was supposedly built by Andronicus of Cyrrhus around 50 BC, but according to other sources might have been constructed in the 2nd century BC before the rest of the forum.

The 12-metre-tall structure has a diameter of about 8 metres and was topped by a weathervane-like Triton that indicated the wind direction. Below the frieze depicting the eight wind deities -Boreas (N), Kaikias (NE), Eurus (E), Apeliotes (SE), Notus (S), Livas (SW), Zephyrus (W), and Skiron (NW) - there are eight sundials. In its interior, there was a water clock, driven by water coming down from the Acropolis above. Recent research has shown that the considerable height of the tower was motivated by the intention to place the sundials and the wind-vane at a visible height, making the tower effectively an early example of a clock tower.



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750-650 BC: Hesiod’s Works and Days    

Ancient bronze bust (now conjectured to be imaginative) of the ancient Greek poet Hesiod (left). An image from a 1539 AD printing of Works and Days (right).


The ancient Greek poet Hesiod presumably lived somewhere between 750 and 650 BC. Hesiod and Homer are generally considered the earliest Greek poets whose work has survived until today, and for that reason they are often paired. In the fourth-century BC Alcidamas' Mouseion they were even brought together in an imagined poetic agon, the Contest of Homer and Hesiod. However, scholars disagree about who lived first, and today it is generally accepted that Homer was the first of these two poets. Much of the summary below is adopted from different sources in Wikepedia and from Rasmussen 2010, from where additional information is available.

Hesiod's writings represent a major source on Greek mythology, farming techniques, early economic thought, archaic Greek astronomy and ancient time-keeping. Hesiod's works are seen from the view of the small independent farmer, while Homer's view is from nobility. Even with these differences, they share some beliefs regarding work ethic, justice, and consideration of material items. Hesiod was in favour of the rule of law and the dispensation of justice to provide stability and order within society. He spoke out against corrupt methods of wealth acquisition and denounced robbery.

Hesiod’s major work Works and Days, a poem of some 800 verses, revolves around two general truths: 1) labour is the universal lot of Man, but 2) he who is willing to work will get by. Scholars have interpreted this work against a contemporary background of agrarian crisis in mainland Greece, during the relatively cold period between the Minoan and the Roman warm periods. This crisis, however, inspired a wave of documented colonisations in search of new land. Works and Days is one of the earliest known musings on economic thought, and at its centre, it is a farmer’s almanac in which Hesiod instructs his brother Perses in the agricultural arts.

In Works and Days Hesiod draws attention to the movement of celestial objects such as the Sun and stars, stating that knowledge on this may be useful for weather forecasting. Among other phenomena, Works and Days contains the earliest recorded mention of the star Sirius, the brightest star seen from Earth (the Greek word for Sirius, is Σείριος, meaning "glowing" or "scorcher"). Hesiod uses a matter-of-fact style, without stating any cause-and-effect, and without associating the celestial objects with any kind of divinity.

Works and Days provides weather advice for both farmers and sailors, and examples of this are given below (translation by Hugh G. Evelyn-White 1914)

Meteorological advice for farmers

(ll. 383-404, extract) When the Pleiades, daughters of Atlas, are rising, begin your harvest, and your ploughing when they are going to set. Forty nights and days they are hidden and appear again as the year moves round, when first you sharpen your sickle. This is the law of the plains, and of those who live near the sea, and who inhabit rich country, the glens and dingles far from the tossing sea, -- strip to sow and strip to plough and strip to reap, if you wish to get in all Demeter's fruits in due season, and that each kind may grow in its season…..

(ll. 414-447, extract) When the piercing power and sultry heat of the sun abate, and almighty Zeus sends the autumn rains, and men's flesh comes to feel far easier, -- for then the star Sirius passes over the heads of men, who are born to misery, only a little while by day and takes greater share of night, -- then, when it showers its leaves to the ground and stops sprouting, the wood you cut with your axe is least liable to worm. Then remember to hew your timber: it is the season for that work…..

Meteorological advice for sailors

(ll. 618-640, extract) But if desire for uncomfortable sea-faring seize you; when the Pleiades plunge into the misty sea to escape Orion's rude strength, then truly gales of all kinds rage. Then keep ships no longer on the sparkling sea, but bethink you to till the land as I bid you. Haul up your ship upon the land and pack it closely with stones all round to keep off the power of the winds which blow damply, and draw out the bilge-plug so that the rain of heaven may not rot it. Put away all the tackle and fittings in your house, and stow the wings of the sea-going ship neatly, and hang up the well-shaped rudder over the smoke. You yourself wait until the season for sailing is come, and then haul your swift ship down to the sea and stow a convenient cargo in it, so that you may bring home profit….

(ll. 663-677, extract) Fifty days after the solstice), when the season of wearisome heat is come to an end, is the right time for me to go sailing. Then you will not wreck your ship, nor will the sea destroy the sailors, unless Poseidon the Earth-Shaker be set upon it, or Zeus, the king of the deathless gods, wish to slay them; for the issues of good and evil alike are with them. At that time the winds are steady, and the sea is harmless. Then trust in the winds without care, and haul your swift ship down to the sea and put all the freight no board; but make all haste you can to return home again and do not wait till the time of the new wine and autumn rain and oncoming storms with the fierce gales of Notus who accompanies the heavy autumn rain of Zeus and stirs up the sea and makes the deep dangerous.


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620-540 BC: Ionian nature philosophers Thales and Anaximander     


Thales of Miletus (left).  Map of Anaximander's universe (centre). Detail of Raphael's painting The School of Athens (right). Presumably this is a representation of Anaximander leaning towards Pythagoras on his left.


Ionia is an ancient region of central coastal Anatolia in the western part of present-day Turkey. Never a unified state, it was named after the Ionian tribe who in the Archaic Period (800-480 BC) occupied mainly the shores and islands of the Aegean Sea. Ionia comprised a narrow coastal strip from near the mouth of the river Hermus in the north to the mouth of the river Meander in the south, and included the islands of Chiros and Samos. Much of the summary below is adopted from different sources in Wikepedia.

Ionia was settled by the Greeks probably during the 11th century BC. Ionia was always a maritime power founded by a people who made their living by trade in peaceful times and marauding in unsettled times. The coast was rocky and the arable land limited. The coastal cities were placed in defensible positions on islands or headlands. The populations of the cities were multi-cultural and received cultural stimuli from many civilizations in the eastern Mediterranean, which resulted in a brilliant society able to make contributions of worldwide and millennial significance.

The philosopher Tales (c.620-c.540 BC) was born in the city of Miletus (Milet in modern Turkey), one of the biggest Ionian cities. Many, most notably Aristotle, regard him as the first philosopher in the Greek tradition. According to Bertrand Russell, "Western philosophy begins with Thales."

By tradition, the Greeks often invoked explanations of natural phenomena by reference to the will of gods and heroes. Thales, however, aimed to explain natural phenomena by a rational explanation that referred to natural processes themselves. For example, he attempted to explain earthquakes by hypothesizing that the Earth floats on water, and that earthquakes occur when the Earth is rocked by waves, rather than assuming that earthquakes were the result of supernatural processes. 

In mathematics, Thales used geometry to solve problems such as calculating the height of pyramids and the distance of ships from the shore. He is credited with the first use of deductive reasoning applied to geometry, by deriving four corollaries to Thales' Theorem. As a result, he has been hailed as the first true mathematician and is the first known individual to whom a mathematical discovery has been attributed. Also, Thales was the first person known to have studied electricity. In addition, it appears that Thales also successfully predicted a solar eclipse.

Thales had a profound influence on other Greek thinkers and therefore on Western history. Many philosophers followed Thales' lead in searching for explanations in nature rather than in the supernatural. Eventually Thales' rejection of mythological explanations became an essential idea for the scientific revolution. He was also the first to define general principles and set forth hypotheses, and as a result he has been dubbed the "Father of Science", though it may be argued that Democritus more correctly deserve this title.  

One of Thales students was Anaximander (c. 610 BC – c. 546 BC). He became famous by explaining how the four elements of ancient physics (air, earth, water and fire) are formed, and how Earth and terrestrial beings are formed through their interactions. His knowledge of geometry allowed him to introduce the gnomon (the part of a sundial that casts the shadow) in Greece. Early sources report that one of Anaximander's more famous pupils was Pythagoras. Anaximander also created a map of the world that contributed greatly to the advancement of geography.

Like many thinkers of his time, Anaximander's contributions to philosophy relate to many disciplines. In astronomy, he attempted a description of the mechanics of celestial bodies in relation to the Earth. In Anaximander's model, the Earth floats very still in the centre of the infinite, not supported by anything.

Anaximander was the first astronomer to consider the Sun as a huge mass, and consequently, to realize how far from Earth it might be. He constructed a celestial sphere and thereby was the first to present a system where the celestial bodies turned at different distances. This presumably this made him the first to realize the obliquity of the Zodiac. His knowledge and work on astronomy also suggest that he must have observed the inclination of the celestial sphere in relation to the plane of the Earth to explain the meteorological changes associated with the annual seasons.

Anaximander saw the oceans as a remnant of the mass of humidity that once surrounded Earth. A part of that mass evaporated under the sun's action, thus causing the winds and even the rotation of the celestial bodies, which he believed were attracted to places where water is more abundant. He explained rain as a product of the humidity pumped up from Earth by the sun. For him, the Earth was slowly drying up and water only remained in the deepest regions, which eventually would dry up as well.  

Anaximander was the first to describe wind as the movement of air (Rasmussen 2010), a notion which later was strongly opposed by Aristotele. Anaximander attributed other meteorological phenomena, such as thunder and lightning, to the intervention of elements, rather than to divine causes. In his system, thunder results from the shock of clouds hitting each other; the loudness of the sound is proportionate with that of the shock. Thunder without lightning is the result of the wind being too weak to emit any flame, but strong enough to produce a sound. A flash of lightning without thunder is a jolt of the air that disperses and falls, allowing a less active fire to break free. Thunderbolts are the result of a thicker and more violent air flow.


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480 BC: Battle of Salamis   

Maps showing movement of the Persian army and navy (red) during the second Persian invasion of Greece 480 BC.


The Battle of Salamis was fought between an Alliance of Greek city-states and the Persian Empire (lead by king Xerxes) in September 480 BC in the straits between the Greek mainland and Salamis, an island in the Saronic Gulf west of Athens. It marked the high-point of the second Persian invasion of Greece which had begun in 480 BC. The main historical source for the Greco-Persian Wars is the Greek historian Herodotus. Much of the summary below is adopted from different sources in Wikepedia, Ancient Mesopotamia and from Rasmussen 2010, from where additional information is available.

To block the Persian advance, a small force of Greeks blocked the now famous pass of Thermopylae, while an Athenian-dominated Allied navy engaged the Persian fleet in the nearby straits of Artemisium. In the resulting Battle of Thermopylae, the rearguard of the Greek force was annihilated, whilst in the Battle of Artemisium the Greeks had heavy losses and retreated after the loss at Thermopylae. This allowed the Persians to conquer much of present-day Greece, although a large part of their navy was destroyed by a strong storm.

After the Battle of Thermopylae, the Allied Greek forces were in a very difficult position. The Athenians knew that their city would surely be destroyed by the Persians when they arrived. There was simply no place between the Persian forces and Athens where the Allied Greeks dared to risk battle. Most of the Greek fleet was withdrawn to the island of Salamis west of Athens, where they watched their city burn.

Notwithstanding the grave military situation, it was considered important by the Athenian statesman Themistocles to bring the Persian fleet to battle, in the hope that a victory would prevent naval operations against the remaining part of Greece. On his side, the Persian king Xerxes was equally anxious for a decisive battle, knowing that winter would soon be arriving-

King Xerxes therefore decided on a naval assault on the remaining Athenians and their naval forces stationed on and at Salamis. The Persian fleet was weakened somewhat because of losses during the previous storm, but it was still a vastly larger force than the Greeks was able to muster. In total, the Persians had around seven hundred ships, the Greeks only around three hundred. The Spartans and other Greek allied ground forces were encamped in the Isthmus of Corinth, awaiting the outcome of the sea battle.

King Xerxes was confident of victory. He had his throne placed on a hill overlooking the sea, in part to savour his victory and in part so his commanders would know that their king was watching them closely. The Allied Greek naval forces were led by Themistocles, who was responsible for devising the tactics used during the battle. However, he was not the admiral who carried out the plan; this was done by Eurybiades, a Spartan commander.

At this stage many of the captains of ships of Athen's allies were threatening to sail away to protect their own city states. Not surprisingly, they feared that the much larger Persian fleet would destroy them. In addition, Eurybiades wanted to move the fleet to the Isthmus of Corinth, where the Allied Greek army were building fortifications. 

However, Themistocles used a ruse to prevent the Allied Greek navy from fleeing. First Themistocles tricked Xerxes into separating his fleet by sending part around the island to blockade the Greek fleet in the sound between Salamis and the mainland so the Greek fleet could not escape. The Persians took the bait and sailed into the strait. Now there was nothing to do for Eurybiades and the Allied Greek navy but to accept Salamis as the battlefield and to fight!


King Xerxes overlooking the naval battle at Salamis 480 BC (left). Greek vessels ramming Persian ships (centre and right).


An essential element of Themistocles offensive strategy was based on a local weather forecast. He was well aware of the daily land-sea breeze, a daily shift between onshore and offshore wind.

  • A sea-breeze (or onshore breeze) is a wind from the sea that develops over land near coasts. It is formed by increasing temperature differences between the land and water which create a pressure minimum over the land due to its relative warmth and forces higher pressure, cooler air from the sea to move inland. 

  • The land-breeze (or offshore breeze) develops during the night, when the land cools off quicker than the ocean due to differences in their specific heat values, which forces the dying of the daytime sea breeze. If the land cools below that of the adjacent sea surface temperature, the pressure over the water will be lower than that of the land, setting up a land breeze. 

  • Usually the strength of the land breeze is weaker than the sea breeze. The land breeze will die once the land warms up again the next morning. 

  • The land-sea breeze phenomenon will only develop when the regional surface wind pattern is not strong enough to oppose it.  

Themistocles expected a sea-breeze to develop shortly after initiating his plan, generating a surface wind towards the Greek mainland, exposing the Persian ships to strong headwinds and waves in the narrow sound between the mainland and the island Salamis and (see map above). The Greek ships were low in their construction, and for that reason stable. In contrast, the Persian ships were of higher construction, and therefore less stable and more difficult to manoeuvre in heavy seas.

The second element of Themistocles strategy was to order the lighter Greek ships rowed out in a circular fashion around the Persian vessels, after which they rammed the Persian vessels by their pointed stern. In the developing sea battle, the waves, the wind, the speed and manoeuvrability of the Greek ships and their knowledge of the local conditions enabled them to sink no less than two hundred of the Persian ships. Some of the Persian ships were captured and the rest fled back to their bases in Asia Minor. King Xerxes, upon seeing this great defeat at Salamis, headed back to Persia with what was left of his navy and part of his army. After the battle Eurybiades was opposed to chasing the Persian fleet, and also to sailing towards the Hellespont to destroy the bridge of ships that the Persian king Xerxes had built there. He wanted Xerxes to be able to escape rather than have him remain in Greece where he would possibly renew the land war.

As a result Xerxes retreated to Asia with most of his army, leaving general Mardonius to complete the conquest of Greece. However, the following year, the remainder of the Persian army was decisively beaten at the Battle of Plataea and the Persian navy at the Battle of Mycale. Afterwards the Persian made no more attempts to conquer the Greek mainland.

The battle of Salamis thus mark a turning point in the course of the Greco-Persian wars as a whole; from then onward, the Greek city-states would take the offensive. A number of historians believe that a Persian victory would have restricted the development of Ancient Greece, and by extension western civilization. It has even been claimed that the sea battle at Salamis is one of the most significant military battles in European history.


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384-322 BC; Aristotle's views on weather and climate    

Marble bust of Aristotle (left). Roman copy after a Greek bronze original by Lysippus c. 330 BC. Geocentric celestial spheres (center); Peter Apian's Cosmographia (Antwerp, 1539). Right picture: Plato (left) and Aristotle (right), a detail of The School of Athens, a fresco by Raphael. Aristotle gestures to the earth, representing his belief in knowledge through empirical observation and experience, while holding a copy of his Nicomachean Ethics in his hand, whilst Plato gestures to the heavens, representing his belief in The Forms.


Aristotle (384-322 BC) was a Greek philosopher, a student of Plato and later teacher of Alexander the Great. Aristotle is one of the most important founding figures in Western philosophy, and his views on the physical sciences profoundly shaped medieval scholarship, and their influence extended well into the Renaissance, although they were ultimately replaced by Newtonian physics. Much of the summary below is adopted from different sources in Wikepedia and from Rasmussen 2010, from where additional information is available.  

Aristotle was born in Stageira in 384 BC, about 55 km east of the modern-day city Thessalonika. His father Nicomachus was the personal physician to King Amyntas of Macedon. Aristotle was trained and educated as a member of the aristocracy. At about the age of eighteen, he went to Athens to continue his education at Plato's Academy. Aristotle remained at the academy for nearly twenty years before quitting Athens in 348/47 BC, and traveling to Asia Minor, where he studied botany and zoology. In 343 BC Aristotle was invited by Philip II of Macedon to become the tutor to his son Alexander the Great. Aristotle was appointed as the head of the royal academy of Macedon and gave lessons not only to Alexander, but also to two other future kings: Ptolemy and Cassander. By 335 BC he had returned to Athens, establishing his own school there known as the Lyceum, where he conducted courses at for the next twelve years. It is during this period in Athens from 335 to 323 BC when Aristotle is believed to have composed many of his works.

Aristotle studied almost every subject possible at the time, and made significant contributions to most of them. In physical science, Aristotle studied anatomy, astronomy, embryology, geography, geology, meteorology, physics and zoology. In philosophy, he wrote on aesthetics, ethics, government, metaphysics, politics, economics, psychology, rhetoric and theology. He also studied education, foreign customs, literature and poetry. His combined works constitute a virtual encyclopedia of Greek knowledge. It has been suggested that Aristotle was probably the last person to know everything there was to be known in his own time. Like his teacher Plato, Aristotle's philosophy was aiming at the universal. Aristotle, however, found the universal in particular things, which he called the essence of things. Aristotle's method is both inductive and deductive, while Plato's is essentially deductive from a priori principles.

In 350 BC Aristotle wrote a treatise entitled 'Meteorologica', which probably is the first attempt ever to make a comprehensive about the earth sciences, including meteorology. 'Meteorologica' consists of four books, including early accounts of water evaporation, weather phenomena, and earthquakes, and was considered a benchmark publication for more than 2000 years. Interesting enough, Aristotle expected clouds to consist of water. In chapter (part) nine in his first book, he directly states that 'air condensing into water is cloud'.

In 'Meteorologica' Aristotle presents a number of interpretations concerning different phenomena related to the Earth, atmosphere, clouds, weather, climate and climate change effects: 

Earth, Sun and atmosphere

  • The earth is surrounded by water, just as that is by the sphere of air, and that again by the sphere called that of fire.

  • ...four bodies are fire, air, water, earth.

  • Fire occupies the highest place among them all, earth the lowest, and two elements correspond to these in their relation to one another, air being nearest to fire, water to earth.

  • ...the motion of these latter bodies [of four] being of two kinds: either from the centre or to the centre.

  • Fire, air, water, earth, we assert, originate from one another, and each of them exists potentially in each, as all things do that can be resolved into a common and ultimate substrate.

  • The efficient and chief and first cause is the circle in which the sun moves. For the sun as it approaches or recedes, obviously causes dissipation and condensation and so gives rise to generation and destruction. 

Clouds and rain

  • Now the earth remains but the moisture surrounding it is made to evaporate by the sun's rays and the other heat from above, and rises. But when the heat which was raising it leaves it, in part dispersing to the higher region, in part quenched through rising so far into the upper air, then the vapour cools because its heat is gone and because the place is cold, and condenses again and turns from air into water. And after the water has formed it falls down again to the earth.

  • Since water is generated from air, and air from water, why are clouds not formed in the upper air? They ought to form there the more, the further from the earth and the colder that region is. For it is neither appreciably near to the heat of the stars, nor to the rays reflected from the earth. It is these that dissolve any formation by their heat and so prevent clouds from forming near the earth. For clouds gather at the point where the reflected rays disperse in the infinity of space and are lost. To explain this we must suppose either that it is not all air which water is generated, or, if it is produced from all air alike, that what immediately surrounds the earth is not mere air, but a sort of vapour, and that its vaporous nature is the reason why it condenses back to water again.

  • However, it may well be that the formation of clouds in that upper region is also prevented by the circular motion. For the air round the earth is necessarily all of it in motion, except that which is cut off inside the circumference which makes the earth a complete sphere. In the case of winds it is actually observable that they originate in marshy districts of the earth; and they do not seem to blow above the level of the highest mountains. It is the revolution of the heaven which carries the air with it and causes its circular motion, fire being continuous with the upper element and air with fire. Thus its motion is a second reason why that air is not condensed into water.

  • The exhalation of water is vapour: air condensing into water is cloud. Mist is what is left over when a cloud condenses into water, and is therefore rather a sign of fine weather than of rain; for mist might be called a barren cloud. So we get a circular process that follows the course of the sun. For according as the sun moves to this side or that, the moisture in this process rises or falls. We must think of it as a river flowing up and down in a circle and made up partly of air, partly of water. When the sun is near, the stream of vapour flows upwards; when it recedes, the stream of water flows down: and the order of sequence, at all events, in this process always remains the same. So if 'Oceanus' had some secret meaning in early writers, perhaps they may have meant this river that flows in a circle about the earth.

  • So the moisture is always raised by the heat and descends to the earth again when it gets cold. These processes and, in some cases, their varieties are distinguished by special names. When the water falls in small drops it is called a drizzle; when the drops are larger it is rain.

Water vapour, dew and hoar-frost

  • Some of the vapour that is formed by day does not rise high because the ratio of the fire that is raising it to the water that is being raised is small

  • Both dew and hoar-frost are found when the sky is clear and there is no wind. For the vapour could not be raised unless the sky were clear, and if a wind were blowing it could not condense.

  • ...hoar-frost is not found on mountains contributes to prove that these phenomena occur because the vapour does not rise high. One reason for this is that it rises from hollow and watery places, so that the heat that is raising it, bearing as it were too heavy a burden cannot lift it to a great height but soon lets it fall again.


  • When there is a great quantity of exhalation and it is rare and is squeezed out in the cloud itself we get a thunderbolt. 

  • So the whirlwind originates in the failure of an incipient hurricane to escape from its cloud: it is due to the resistance which generates the eddy, and it consists in the spiral which descends to the earth and drags with it the cloud which it cannot shake off. It moves things by its wind in the direction in which it is blowing in a straight line, and whirls round by its circular motion and forcibly snatches up whatever it meets.

Climate change effects:

  • So it is clear, since there will be no end to time and the world is eternal, that neither the Tanais nor the Nile has always been flowing, but that the region whence they flow was once dry: for their effect may be fulfilled, but time cannot. And this will be equally true of all other rivers. But if rivers come into existence and perish and the same parts of the earth were not always moist, the sea must needs change correspondingly. And if the sea is always advancing in one place and receding in another it is clear that the same parts of the whole earth are not always either sea or land, but that all this changes in course of time.


Aristotle's writings never were to influence directly on practical meteorology. For many centuries people relied instead on a number of weather rules of thumb, some times mixed up with assuming a certain degree of divine interference. One of Aristotle's students, Theophrastus (371-287 BC)  succeeded him as a director of the Lyceum in Athens. He took over the philosophy of Aristotle in parts reshaping, commenting, and developing it in an original way. His thinking leads to empirism by means of observation, collection, and classification. He was around 35 years the director of the Lyceum and he was a teacher of up to 2000 students. Theophrastus is today often considered the "father of botany". In addition, he probably was the first in Europe to discover Sunspots (although observed independently and much earlier in China). However, he also continued Aristotle's work on meteorology, formulating about 80 weather rules, based on observations. This indicates that empirical meteorology already at this time had reached an advanced stage in Greek science.

Later, much of the knowledge acquired and formulated by Aristotle and his students was ignored and forgotten in Europe, and it was not before 1000-1100 yr AD that it was rediscovered by European scientist, after surviving among Arabian scientists. By this, however, the theories and other explanations set forth by Aristotle were to gain huge impact on the following European scientific development.


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200-0 BC: European Science and Meteorology in the balance: Alexandria and Rome  


The Royal Library of Alexandria, or Ancient Library of Alexandria, in Alexandria, Egypt, was probably the largest, and certainly the most famous, of the libraries of the ancient world. It flourished under the patronage of the Ptolemaic dynasty, and functioned as a major centre of scholarship, at least until the time of Rome's conquest of Egypt, and probably for many centuries thereafter.


Around 200 BC the Greek centre of science has more or less ceased to exist, and most of the previous scientific activity had moved away from Europe to Alexandria in the Nile delta. Alexandria was founded around a small pharaonic town c. 331 BC by Alexander the Great. Within a century, Alexandria had become the largest city in the world and, for some centuries more, was second only to Rome. It became Egypt's main Greek city, with Greek people from diverse backgrounds. It remained Egypt's capital for nearly a thousand years, until the Muslim conquest of Egypt in AD 641. Much of the summary below is adopted from different sources in Wikepedia and from Rasmussen 2010, from where additional information is available.  

The Royal Library of Alexandria, or Ancient Library of Alexandria, was the largest and most significant library of the ancient world. It flourished under the patronage of the Ptolemaic dynasty and functioned as a major centre of scholarship from its construction in the 3rd century BC until the Roman conquest of Egypt in 30 BC. Apparently the library was initially organized by Demetrius of Phaleron, a student of Aristotle, under the reign of Ptolemy Soter (ca.367 BC—ca.283 BC). The library had about 500,000 books in its collections and also comprised gardens, a room for shared dining, a reading room, lecture halls and meeting rooms. The influence of this model may still be seen today in the layout of many university campuses. The library itself is known to have had an acquisitions department, and a cataloguing department. A hall contained shelves for the collections of scrolls (books were at this time on papyrus scrolls), known as bibliothekai. Legend has it that carved into the wall above the shelves was an inscription that read: The place of the cure of the soul.

The first known library of its kind to gather a serious collection of books from beyond its country's borders, the Library at Alexandria was charged with collecting the entire world's knowledge. It did so through an aggressive and well-funded royal mandate involving trips to the book fairs of Rhodes and Athens, supplemented by a policy of pulling the books off every ship that came into port. They kept the original texts and made copies to send back to their owners.

Other than collecting works from the past, the library was also home to a host of international scholars, well-patronized by the Ptolemaic dynasty with travel, lodging and stipends for their whole families. As a research institution, the library filled its stacks with new works in mathematics, astronomy, physics, natural sciences and other subjects. In this way much of the knowledge acquired and formulated by Aristotle and his students were kept alive after the golden period of science had ceased in Greece, and for a period, Alexandria became the new scientific center in the Mediterranean area. Part of the reason for the golden period of science coming to an end in Greece was the growing power of the Roman Republic and later the Roman Empire, spreading throughout the Mediterranean.

The Roman Republic was the period of the ancient Roman civilization where the government operated as a republic. It began with the overthrow of the Roman monarchy around 508 BC, and its replacement by a government headed by two consuls, elected annually by the citizens and advised by a senate. A complex constitution gradually developed, centred on the principles of a separation of powers and checks and balances. Except in times of dire national emergency, public offices were limited to one year, so in theory at least, no single individual could dominate his fellow-citizens.

The Roman Republic was gradually weakened through several civil wars, and several events are commonly proposed to mark the transition from Republic to Empire, including Julius Caesar's appointment as perpetual dictator (44 BC) and the Battle of Actium (2 September 31 BC).

Roman expansion began in the days of the Republic, but the Empire reached its greatest extent under Emperor Trajan: during his reign (98 to 117 AD) the Roman Empire controlled approximately 6.5 million km2 of land surface. Because of the Empire's vast extent and long endurance, the institutions and culture of Rome had a profound and lasting influence on the development of language, religion, architecture, philosophy, law, and forms of government in the territory it governed, particularly Europe, and by means of European expansionism throughout the modern world.

Both the Roman Republic and the Roman Empire, however, had little interest in science. Scientific knowledge was only regarded as relevant from an applied point of view, and basic research was neither interesting nor encouraged by the society. This is why the Library at Alexandria for some time developed into a safe haven for much of the knowledge, including meteorological, which has been developed by Aristotle and his students in Greece during the golden period.

At the same time, Christianity was increasing its influence rapidly in Europe, and the Greek scientific knowledge was increasingly considered as an expression of old paganism, and for that reason something which should be subjected to suppression and ban. As the political influence of Christianity grew in Europe and across the entire Mediterranean region, it became more and more difficult for the Library at Alexandria to carry on as previously. Eventually, many of the scientists associated with the Library were exposed to persecution. Many therefore had to leave Alexandria and instead moved to Damascus, into the growing Arab Caliphate, where science and scientists were welcomed. So once again, the scientific tradition and knowledge established by Aristotle and his students had to move and survive outside Europe. 


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120-114 BC:  The Cimbrian flood and the following Cimbrian war 113-101 BC    

The migrations of the Cimbri and the Teutons between 113 and 101 BC (left diagram), with places of major battles with Roman forces indicated. Drawing showing Cimbrian people during their European journey (right).


The Cimbrian flood (or Cymbrian flood) was a large-scale incursion of the North Sea in the region of the Jutland peninsula (Denmark) in the period 120 to 114 BC, resulting in a permanent change of coastline with much land lost. The flood was caused by one or several very strong storm(s). A high number of people living in the affected area of Jutland drowned, and the flooding apparently set off a migration of the Cimbri tribes previously settled there (Lamb 1991). Most likely the Cimbrian flood was the result of the gradual flooding of the present North sea since the end of the last (Weichselian) glaciation, in combination with a stormy period, presumably influenced by a period of global cooling (see below).

The Cimbri were a tribe from Northern Europe, who, together with the Proto-Germanic Teutones and the Ambrones threatened the Roman Republic in the late 2nd century BC. Most ancient sources categorize the Cimbri as a Germanic tribe, but some authors include the Cimbri among the Celts ( Old sources located their original home in Jutland, which was referred to as the Cimbrian peninsula throughout early historical times. As an example, on the map of Ptolemy, the "Kimbroi" are placed in the northernmost part of the Jutland peninsula, in the modern Danish region Himmerland, shortly south of the sound Limfjorden. The moden Vendsyssel-Thy region of Denmark north of Limfjorden was at that time still mainly a group of islands. Himmerland (Old Danish Himbersysel) is generally thought to refer to the name Cimbri. However, the precise origin of the name Cimbri is unknown.

Some time before 100 BC many of the Cimbri, as well as the Teutons and Ambrones migrated south-east. After several unsuccessful battles with the Boii and other Celtic tribes, they appeared ca 113 BC on the Danube, in Noricum, where they invaded the lands of one of Rome's allies, the Taurisci. On the request of the Roman consul Gnaeus Papirius Carbo, sent to defend the Taurisci, they retreated, only to find themselves deceived and attacked at the Battle of Noreia. Here they nevertheless defeated the Roman army seriously. Only a storm, which separated the armies, saved the Roman forces from complete annihilation.

However, Rome was however finally victorious in the Cimbrian war, and the Cimbri-Teutonic forces  - who had inflicted on the Roman armies the heaviest losses that they had suffered since the Second Punic War with victories at the battles of Arsusio and Noreia – were almost completely annihilated, during the battles at Aquae Sextiae and Vercellae.

The timing of the war had a great effect on the internal politics of Rome, and the organization of its military. The war contributed greatly to the political career of Gaius Marius, whose consulships and political conflicts challenged many of the Roman republic's political institutions and customs of the time. The Cimbrian threat, along with the Jugurthine War, inspired the landmark Marian reforms of the Roman legions.


Gundestrup cauldron (left). Plate E from the Gundestrup Cauldron (right), apparently showing Roman warriors.


The Gundestrup Cauldron is the largest known example of European Iron Age silverwork. It is 69 cm in diameter and 42 cm in height, and weighs almost 9 kg. It has been dated to the period between 130 BC and 1 BC. The cauldron is made up from 13 separate plates - 5 long rectangular plates that form the interior; 7 short rectangular plates that form the exterior; and one round base plate, together with the shallow, curved, undecorated base. The cauldron was found in Himmerland on May 28, 1891, by peat cutters working in a small peat bog called Rævemose, near Gundestrup.

This unique piece of artwork suggests that there was contact between Jutland and southeastern Europe, but it is uncertain if this contact can be associated with the Cimbrian migration. Neither has archaeologists found any clear indications of a mass migration from Jutland around this time, and presumably it was only the tribes living in the areas directly affected by the flood and subsequent sand drifting which decided to move south.

But why did the Cimbrian Flood occur about period 120 to 114 BC? Presumably the explanation is partly to be sought in the diagram below, showing the flood to occur in the latter part of a relatively cold period shortly before the Roman Warm Period. 



The upper panel shows the air temperature at the summit of the Greenland Ice Sheet, reconstructed by Alley (2000) from GISP2 ice core data. The approximate timing of the Cimbrian Flood is in the latter part of the cold period before the Roman Warm Period. The time scale shows years before modern time, which is shown at the right hand side of the diagram. The rapid temperature rise to the left indicate the final part of the even more pronounced temperature increase following the last ice age. The temperature scale at the right hand side of the upper panel suggests a very approximate comparison with the global average temperature (see comment below). The GISP2 record ends around 1855, and the red dotted line indicate the approximate temperature increase since then. The lower panel shows the past atmospheric CO2 content, as found from the EPICA Dome C Ice Core in the Antarctic (Monnin et al. 2004). The Dome C atmospheric CO2 record ends in the year 1777.


Whenever the planet cools, the cooling is especially pronounced near the poles and smaller near the Equator. The planetary cooling therefore produces an enhanced thermal contrast between equatorial regions and the poles. In the northern hemisphere, this thermal contrast tends to develop especially in latitudes between about 50 and 65oN, in the so-called zone of westerlies. Global cooling and the strengthened north-south thermal gradient is the basis for development of stronger cyclonic storms over oceans in the zone of westerlies, leading to increasing flood frequency and damage for adjoining coasts and land areas, especially around the North Sea.


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