There is also variations between polar regions. As the north pole experiences summer the south pole experiences winter. The north and the south are closer to the sun at different times of the year. Summer solstice occurs on the southern hemisphere around 21st December while the north experiences summer. In both hemispheres, first day of winter solstice marks first day of astronomical summer similar to the first day of winter solstice.
When the earth is not tilted on its axis, these polar regions experience spring and autumn. This phenomena is referred to as equinox. These are times when the earths axis is pointed parallel to the sun instead of being towards or away from it. Days and nights during the equinox are equal. Spring on equinox happens around 20th March on the northern hemisphere while the southern hemisphere experiences autumn. Vernal or spring equinox starts on 20th September on the southern hemisphere as the north experiences autumn. In both hemispheres, first day of autumnal equinox marks first day of fall. The same holds for the first day of the vernal or spring equinox.
There are other factors that affect temperature and weather conditions over seasons. For instance mountainous regions experience more ice on winter than the plains. Some areas experience dry summers while some experience wet summers. Coastal regions may experience violent tropical storms.
Seasonal points are preceded by weather conditions. This is because seasonal change does not happen at an instant but over a given period. Meteorological seasons are based on these changes. Here, seasons are assigned to three months which show weather consistency. The northern hemisphere experiences winter from December to February. Spring on the north and autumn on the south is experienced from March to May. Months of summer are June, July and August. From September to December comes autumn on the north and spring on the south.
These seasons have a huge impact on life on earth. Activities carried out in each location depends on the prevailing weather. For example people go skiing on winter when there is ice. Also, swimming happens during summer. Animals migrate, hibernate or mate depending with seasons. Plants germinate, bear fruits and weather depending with seasons. Conditions are only favorable for specific activities. Each season comes with its own threats and sustenance.