Distribution of temperature on the earth’s surface is not even everywhere. Therefore, the distribution of temperature has the maximum effect of latitudes as compared to other factors. Based on the temperature, the world is divided into three zones. There is a close connection between insolation and temperature.
The distribution of heat is mainly divided into two types:
1. Horizontal distribution of temperature: The horizontal distribution’ of temperature means the latitudinal distribution of temperature. There is change in the distribution of temperature from the equator to the poles. The temperature distribution on the map is represented by the isotherms. In most parts of the world, minimum and maximum temperatures are found in the months of January and July. Therefore, for analyzing temperature, the months of January and July are usually chosen.
Isotherms of January: In January, the sun rays fall vertically on the Tropic of Capricorn in the southern hemisphere, due to which the southern hemisphere has summer season and the northern hemisphere has winter season. Therefore, the temperature in the southern hemisphere is high and the temperature in the northern hemisphere is low.
Meanwhile, the coldest parts are located in Siberia and Greenland. The isotherms of 25°C are stretched over the vast area of Siberia. On the southern continents, the isotherms of 30°C and in the southern hemisphere the isotherms of 10°C are parallel to the latitudes, while the isotherm of 20°C is a twisted line according to the distribution of continents and oceans. Isotherms have been made quite curved due to the uneven distribution of water and land in the Northern Hemisphere.
Isotherms of July: In July, the rays of the sun shine almost vertically on the Tropic of Cancer in the northern hemisphere. Thus, in the northern hemisphere there is summer season and in the southern hemisphere there is winter season. In July, the isotherm of 30°C is enclosed in North Africa, the South – Western and Central Asia, and the Columbia Plateau in North America.
In comparison with the isotherms of January, it is clear that the effect of summer is on more areas in July. During this time, there is minimal temperature in Antarctica. The isotherms in the southern hemisphere have often been drawn parallel to the axes latitudes.
2. Vertical distribution of temperature: By the vertical distribution of temperature we mean the distribution of temperature, in different layers of the atmosphere above the earth’s surface, at different altitudes. Scientists have proven it on the basis of facts that the temperature decreases as the height increases. This is the reason that the hills are colder than the plains.
There is a decrease of 1°C in temperature at a height of every 165 meters, which is called normal temperature lapse rate. This rate is not the same at every place, but according to the season, condition and local turbulence, it keeps changing. Normally, the temperature decreases at a rate of 6.4°C per km. The decline in temperature continues till the troposphere. After this, the decrease of temperature stops.
