How are the climatic zones formed?
Over the continents and oceans, large air masses are formed , homogeneous in properties. Properties are expressed in the ratio of heat and moisture. If the air mass was formed over the cold continent, then by properties it will be dry and cold. The ocean saturates the atmosphere with moisture. In hot latitudes, air heats up and loses moisture.
On the globe, alternating warm and cold belts, so the air masses also alternate in the direction from the poles to the equator. Arrays of air, similar in properties, seem to encircle the planet and determine the type of climatic belt.
The tropical climate is characteristic of tropical latitudes, and subtropical for subtropics. According to geographical classification, the climate belt in the tropics refers to the main belts, and the subtropical one to the transition belts.
The main characteristics of the tropical climate
The tropical climate zone is between the equator and the tropics in the northern and southern hemisphere. The tropic line is a parallel of 23.5 0, the last from the equator, where the solstice is observed 2 times a year.
The zone of the tropics is geographical latitudes with increased atmospheric pressure. Therefore, air from here spreads in those directions where the pressure is low. For the zone of the tropics is characterized by a constant movement of air, which caused the formation of winds called trade winds.
Tropics are the territory of the highest year-round temperatures , where the thermometer does not fall below +18 0 С during the year , and in the deserts the temperature can reach +50 0 С. The amount of precipitation falling in a year is up to 200 mm.
The climatic belt of the tropics is divided into two subzones:
- With a tropical dry climate (continental continents);
- With a tropical humid climate (areas of the equator on all continents).
Dry subtropics are characteristic for the mainland part of the climatic zone, and wet ones for the oceanic islands. On the mainland of the tropical belt are the most famous vast deserts of the world.
The main characteristics of the subtropical climate
The subtropics extend between the tropics and latitudes with a temperate climate within the boundaries of the parallels of 23.5 0 and 35 0 of the northern and southern hemispheres, but occasionally found in slightly larger latitudes. As for all transitional belts, the change in the dominant air masses is typical for subtropics twice a year. As a result of the global circulation of the atmosphere for six months in the subtropics comes the air from the north, and for the other half a year – from the south. So in the northern hemisphere in the subtropics in the winter comes cold moderate air, and in the summer – dry and hot air of the tropical zone. Seasons of the year are defined as a non-tropical winter and a tropical summer.
This implies a large seasonal difference in temperature and precipitation. But the average annual temperature still remains positive and holds at around +14 0 C.
According to the degree of moistening in the subtropical belt of each continent, the following subzones are distinguished:
- Arid (Mediterranean) climate with maximum precipitation in winter and mild summer.
- Dry subtropics with low average annual precipitation.
- Semi-moist subtropics.
- Wet subtropics.
Despite the listed internal differences, among the subtropics there is not one territory, according to characteristics similar to the tropics.
What are the main differences of the tropical and subtropical climate
So, two climatic zones – tropical and subtropical, located in the hot belts of the Earth, have significant differences.
- Geographical position. Each of the climatic zones has a latitudinal position within the boundaries of certain parallels. They do not overlap .
- The prevailing air masses forming the climatic belt. The climate of the tropical belt forms hot and dry air over the mainland and air masses moist over the ocean. Temperate and tropical air alternate in the subtropics.
- Strong seasonality . In the tropics there is no pronounced weather seasonality, since tropical air has the same properties year-round. Warm and cold periods are expressed in the subtropics, albeit with a slight temperature difference and positive average annual temperatures.
- Constantly operating winds . For the tropics, trade winds are characteristic – constant winds blowing in the northern hemisphere from north to east all year round, and in the southern hemisphere from north to west. The reason for their formation is the difference in pressure between the tropics and the equator. In the subtropics, air flows with a constant directional motion are not formed.
- Average annual temperatures . In the tropical zone, the average annual temperatures are + 25-30 0 С, the maximum values are more than +50 0 C. In the subtropics, the mean annual temperatures are also positive, but the contrast between winter and summer temperatures is observed: from +4 0 C to +20 0 С. Absolute The values of both winter and summer temperatures differ greatly from the average for the year in both directions.
- The amount of precipitation . The tropical belt is the dryest belt of the Earth, where the average annual precipitation is less than 200 mm of precipitation. In the subtropics the amount of precipitation varies according to the seasons of the year, therefore within the belt there are zones with their maximum number from 500 to 700 mm per year, and zones with a minimum of 100 mm per year.
- Suitability for economic use . The tropical zone due to the aridity of the climate is not suitable for economic activities. In the semi-desert regions, only a few branches of livestock production have developed on a large scale. Potential for crop production is limited. The climate of the subtropics has all the conditions for the development of agriculture, gardening and recreational facilities. The famous large resort centers of the Mediterranean, the North American coast and South-East Asia are located in the subtropical belt and receive an enormous number of tourists every year.