Since the Earth is round and not flat, the Sun's rays don't fall evenly on the land and oceans.
The Sun shines more directly near the equator, bringing these areas more warmth.
However, the polar regions are at such an angle to the Sun that they get little or no sunlight during the winter, which causes colder temperatures.
These differences in temperature create a restless movement of air and water in great swirling currents to distribute heat energy collected from the Sun across the planet.
When air in one region is warmer than the surrounding air, it will become less dense and begins to rise, ultimately drawing more air in underneath.
Elsewhere, the cooler air (which is more dense) sinks downward, pushing air outward to flow along Earth's surface, thus completing the cycle.
This movement of the air causes different weather situations to be pushed in and out of any particular location on a day-to-day basis.