Due to the Earth’ inclination at 66 1/2°and revolution, we recognize a few special latitudes on the globe. The vertical rays of the Sun strike the Earth at different points at different times of the year. On March 21st and September 23rd it falls on the middle of the Earth i.e., Equator. On June 21st the vertical rays fall on 23 1/2° North – Tropic of **** and on December 22nd it falls on 23 1/2° South- Tropic of Capricorn. On June 21st the Sun’ rays reach 66 1/2° South Antarctic circle. The North Pole (90° south) is the two ends of the Earth’* axis.
On the basis of special latitudes the globe may be divided into ‘Temperature zones’ or ‘ Heat zones’. Direct rays of the sun produce more heat than the slanting rays. The region near the equator receives more direct rays of the Sun. These rays are intense over smaller areas and so it heats up the Earth more. As we go away from the equator, the sun’ rays strike the Earth’ surface with slanting rays, spreading over a larger area so, they do not heat as intensely as the direct rays. Therefore, when we go from the equator to the poles, we come across zones with varying temperatures.
The Torrid Zone The zone stretches between 231/2°N and south latitudes and more or less receives the vertical rays of the sun. As a result, this region experiences moderately warm climate throughout the year.
The Temperate zone: In between the Torrid and the frigid zones i.e., between 23 1/2°N and South and 66 1/2°N and ** the Temperate Zone. In this zone the sun’ rays fall obliquely and hence the region experiences a moderate climate.
The Frigid Zone: This zone extends from Arctic Circle to North Pole (66 1/2°N to 90°N) in the Northern Hemisphere and the Antarctic circle to South Pole (66 1/2° to 90° ) is known as ‘Frigid Zone’. Since the sun’* rays fall extremely obliquely in this region, the region experience extremely cold climate.
