Normally, we will be having a person in every group who has visited abroad and we will be surprised by hearing the stories of low temperature he experienced during his stay over there, especially if we are from a tropical country and he traveled to some temperate country like England. Then, we will start to wonder why are we experiencing hotness while they are experiencing cold climate.
So lets get to know the reason....
One of the major factors that determines the climate of a region is latitude (an imaginary line that runs from east to west around the earth in both northern and southern hemispheres to determine the location on earth).
Generally, lower latitudes (Equator 0º) have high temperature than higher latitudes (poles 90ºN and S) as sun rays hit directly over the equator concentrated over a small area and towards poles the sun rays are in a slant position concentrated over a wider area. In Fig. 1. you can see the sunlight incidence over different regions of the earth. To understand simply, see Fig. 2. in which the light directly overhead covers a smaller area with full intensity (like equator) and when the light is at an angle to the surface the intensity reduces and covers a large area (like polar region). The same difference is experienced by the earth when sunlight reaches the surface.
This is the reason for hot tropic climate near the equator and freezing cold climate near the poles. Thus, when one moves from the equator towards poles, temperature will be less due to difference in intensity and angle of sunlight.
Fig. 1. Sunlight incidence on earth Fig. 2. Illumination in different angles
Image source: bio.miami.edu Image source: geography.name
The Fig. 2. shows the average annual temperature of the earth and you can notice decrease in temperature from the equator towards the poles.
Fig. 2. Average annual temperature in ºC
Image source: Research paper by Mr.Monjur Mourshed
So, now we understood the difference in temperature over different latitudes. But still some of us will be confused of different temperature over same latitude. Why does this happen?
This is because not only the latitude decides the temperature of a region, but other factors like altitude (hilly regions), nearness to sea (coastal regions) and so on has influence in deciding the temperature of a region.
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