Wind is a motion of air. Air always moves from a place of higher air pressure to a place of lower air pressure. The cause for higher air pressure can be a higher temperature which can be caused by the sun. As the amount of sunshine (duration of daylight and warmth) depends on the season, predominant wind directions are (at least partially) connected to the seasons. In modern geoscience, this can be understood through the concept of the tropical wind circulation. Although lacking knowledge about the causes of the seasonal winds, ancient scholars already noticed them as a natural phenomenon. For them, it was striking that typical seasonal winds always occur simultaneously with the heliacal rising of the same stars or constellations or always when the full moon or crescent moon stands in a specific constellation.

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From ancient Mesopotamia, the earliest astronomical compendium, MUL.APIN, dating to the later half of the second millennium BCE. In its second part, lists of predominant wind directions with typical seasons are given.

While the centre of the tropical wind system shifts from the southern to the northern tropics and back during the course of the year, the northern and southern circulation cells follow this motion accordingly. In the northern summer, the inter tropical convergence zone lies roughly at the northern tropic and the northern cell of the trade wind system lies above the Mediterranean. This causes a rather stable trade wind in the Aegean Sea which is also influenced by a local monsoon effect (i.e. the gradient of air pressure above land and sea) and is therefore called Etesian Wind.