Seasons, Change of

Climate and Geography

According to the Koeppen climate classification, generally torrid or tropical climates include the tropical rainforest, the tropical savanna and the tropical monsoon, all of which have rainy and dry seasons. The rainy season in the tropics tends to follow the sun's direct rays between the tropics of Cancer and Capricorn. The direct rays bring about convection currents in the atmosphere from the heating of the earth's surface, and as the heated air rises it cools. When the air cools sufficiently, condensation occurs and clouds form. Once the clouds become saturated enough with moisture, rain occurs, bringing with it the rainy season. At this time in other parts of the tropics, the dry season occurs; sometimes, depending on location, there are two dry seasons and two wet seasons. However, even during the dry season, varying amounts of rain will fall occasionally during the afternoon. The dry season (or seasons) in the tropics occurs where the sun is not directly striking the earth's surface, resulting in a significant decrease in convection currents and very little, if any, precipitation.

The temperate zones are located in the northern and southern hemispheres and vary with the position or angle of the earth as related to the sun. Thus, when it is winter in the northern hemisphere, it is summer in the southern hemisphere, and vice versa. The transitional seasons between winter and summer are spring and fall. The temperate zones as mirrored as the hemispheres exhibit several temperate climates. Nearer to the tropical zone, the humid subtropical, marine West Coast, and Mediterranean climates occur. The humid subtropical climate tends to have four seasons, with mild winters and hot summers. The marine West Coast climate is cool and rainy most of the year. The Mediterranean climate has a cool, wet winter and a hot, dry summer. Nearer to the polar zone, but only in the northern hemisphere, are the humid continental with a warm summer, the humid continental with a cool summer, and the Subarctic climate. The humid continental climates exhibit the well-known and typical winter, spring, summer, and fall seasons. Winter [Page 1146]snows, spring rains, summer breezes and colorful falls dominate the landscape. The subarctic climate, adjacent to the polar tundra, is commonly known as the taiga biome, with stunted conifers that survive a harsh winter and a short growing season. The continental climate types do not appear in the southern hemisphere, where there is more water than land, the underlying reason being that water heats and cools more slowly than land.

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