It is all a matter of the angle the sun makes with a pole struck in the ground at local time of noon, when the sun is highest in the sky.
Near the equator, the sun's rays are coming in at a steep angle close to 90 degrees. This means that the sun's rays are concentrated.
On the other hand at high latitudes , the sun's rays are coming in at a relatively shallow angle...so the rays get spread out over a larger area.
Hence the heat per unit area is HIGHER at low latitude compared to HIGH latitude.
The effect of this uneven heating, caused ultimately by the tilt of the Earth's own axis, is to give rise to what is called Hadley circulation...
Hot air rises in equatorial regions and then moves north and south (towards the poles). As it moves it gives up its heat and eventually sinks down near the poles and flows south or north (depends on hemisphere) towards the equator to pick up more of the concentrated heat from the sun.
A simple way to imagine this is to get a basketball and shine a flash light at it along its equator...up near the pole, the light rays will come in almost parallel to the surface! very weak light! But near the equator, the light will be concentrated, because the rays are perpendicular to the (local) surface.
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