There are a number of factors that determine the horizontal distribution of temperatures. It has already been pointed out that the effectiveness of insolation in heating the earth’s surface depends on latitude.
We also know that there is a general decrease in temperature from the equator towards the poles. However, if the effect of latitudinal variation in the receipt of solar insolation were the only control of temperature distribution, the isotherms on a world temperature map would have been exactly parallel to the parallels of latitude.
But in spite of the fact the isotherms generally trend east-west, they are highly irregular. The isotherms over certain parts of the globe are closely spaced, while elsewhere they are widely spaced.
This is a clear proof of the wide variation in the temperature gradient in various parts of the world. Besides, the isotherms showing the distribution of temperature develop a number of bends and deformities in shapes.
Following are the additional factors that also affect the distribution of temperature on the earth surface:- (a) differential heating of land and water, (b) effect of ocean currents, (c) mountain barriers, and (d) topographic relief.