Name a country in the Temperature Belt of the Northern hemispjere and in the Southern hemisphere
Answers
Air is a mixture of several gases. Gas molecules are in constant state of collision and move freely. Pressure of air at a given place is defined as a force exerted against surface by continuous collision of gas molecules. Air pressure is thus defined as total weight of a mass of column of air above per unit area at sea level. The amount of pressure exerted by air at a particular point is determined by temperature and density which is measured as a force per unit area.
The unequal heating of the earth and its atmosphere by the sun, because of revolution of the earth on its tilted axis causes difference in pressure. This leads to the formation of pressure belts around the earth.
a) Equatorial low pressure belt:
At the Equator heated air rises leaving a low-pressure area at the surface. This low pressure area is known as equatorial low pressure. The pressure belt is thermally induced because the ground surface gets heated during the day. This area extends between 50N and 50S latitudes. The zone shifts along with the northward or southward movement of sun during summer solstice and winter solstice respectively.
b) Sub-tropical High pressure belt:
The warm air risen up at the equator due to heating reaches the troposphere and bend towards the pole due to rotation of the Earth. Due to coriolis force the air descends at 30-35º latitude thus creates the belt of sub-tropical high pressure. The pressure belt is dynamically induced as it owes its origin to the rotation of the earth and sinking and settling of winds. This zone is characterized by anticyclonic conditions which cause atmospheric stability and aridity. Thus, most of the hot deserts of the world are present in this region extending between 25-35 degrees in both the hemisphere.
c) Sub-Polar Low Pressure Belt:
This belt is located between 60-65 degrees latitudes in both the hemisphere. This pressure belt is also dynamically induced. As shown in the figure the surface air spreads outward from this zone due to rotation of the earth thus produces low pressure. The belt is more developed and regular in the southern hemisphere than the northern due to over dominance of water in the former.
d) Polar High Pressure Belt:
High pressure persists at the pole on both the hemisphere due to low temperature. Thus the Polar High Pressure Belt is thermally induced as well as dynamically induced as the rotation of earth also plays a minor role.
The primary cause of the seasons is the 23.5 degree of the Earth's rotation axis with respect to the plane of the ecliptic, as illustrated in the adjacent image (Source). This means that as the Earth goes around its orbit the Northern hemisphere is at various times oriented more toward and more away from the Sun, and likewise for the Southern hemisphere, as illustrated in the following figure.