Climate is one of the most complex of all Earth systems. Many other systems play a role in determining climate: the water cycle, atmospheric conditions, the carbon cycle, and even plate tectonics and vulcanism. Scientists are still working to understand the ways that these various factors affect climate.

Solar energy is the main engine of our climate. The sun heats the earth unevenly—solar energy is greatest at the equator and weakest at the poles. That's because, as latitude increases, the sun's rays strike the earth at an angle, diffusing the solar energy.

These differences in energy cause temperature differences. How?