 The radiation emitted by the Sun spreads out fairly uniformly as a sphere as it travels away from the Sun and by the time it reaches the top of Earth's atmosphere, it's fairly uniform at around 1360 watts per square meter. Now this incoming solar radiation hits the equatorial regions at a normal angle so they cop the full amount square on. The polar regions however are at an oblique angle to the incoming solar radiation so the incident radiation tends to be smeared out over a much larger area which is dependent on the latitude so the higher the latitude the less incoming solar radiation. So if you were to look at the latitudinal distribution of the incoming solar radiation at the top of the atmosphere you'd find that it has a peak at the equator and it drops off to minima at the poles. So that was the incoming radiation from the Sun. Now for Earth to be in somewhat of a thermal equilibrium this incoming radiation must be balanced by outgoing radiation from Earth back out to space. The outgoing radiation is simply a function of the local temperature. Now we know that it is relatively warm at the equator and relatively cool at the poles so the latitudinal distribution of the outgoing radiation is such that it's a maximum at the equator and a minimum as you go towards the poles. This latitudinal distribution is just like the incoming solar radiation however if you compare the incoming and outgoing solar radiation distributions you'll find that there is more incoming than outgoing at the equator and there's more outgoing than incoming at the poles. This means that there is a net heat gain at the equator and a net heat loss at the poles. Now if there's a net heat gain in some region we know that the temperature there will continue to increase. At the same time if there's a net heat loss in some region the temperature there should tend to decrease. Now on the long time scales of Earth the equatorial regions haven't been continuously increasing their temperature nor have the polar regions been continuously decreasing their temperature they're somewhat steady over a long long period of time. So there must be some mechanism on Earth that's actually taking excess heat from the equator and transporting it to the polar regions. Now this mechanism of course is our climate, Earth's climate and the heat transport is predominantly performed by the atmosphere and the ocean.