One of the four equal periods into which the year is divided by the equinoxes and solstices, resulting from the apparent movement of the sun north and south of the equator during the course of the earth's orbit around it. These periods (spring, summer, autumn and winter) have their characteristic weather conditions in different regions, and occur at opposite times of the year in the N and S hemispheres.
One of the natural periods into which the year is divided by the equinoxes and solstices or atmospheric conditions