Global atmospheric circulation

There are several reasons why energy is moved around the atmosphere:

Solar energy enters the atmosphere. Equatorial regions get the most.
There is more energy at the tropics than at the poles, creating an imbalance.
As warm air rises and cold air sinks it forms three atmospheric circulation cells north of the equator and three to the south.
These circulation cells move over land and sea to redistribute the energy, from the equator to the poles in both hemispheres, trying to even out the energy imbalance.