A season corresponds to a period of the year when there is a certain climatic constancy. They are opposite in the northern hemisphere and in the southern hemisphere and are four in number: winter, spring, summer and autumn.

These seasonal climatic variations come from the tilt of the earth’s axis of rotation and the exposure to the sun of a part of the globe. In July-August the northern hemisphere will be the most exposed to the sun and the southern hemisphere the least. In January-February it will be the opposite. Thus the seasons will be opposite in the two hemispheres.

The first day of spring and autumn will be marked by the equinoxes and the first day of summer and winter will be marked by the solstices, which are again opposite in the northern and southern hemispheres.

It is interesting to mention that on the equator, although seasons exist in the calendar, they show almost no climatic variation. In the city-state of Singapore, for example, the weather is almost the same throughout the year.