Wind is created by the uneven heating of Earth's surface and atmosphere. Different substances on the planetary surface absorb solar radiation at different rates. Warmer air expands to create a pressure difference that produces wind, the movement of air that occurs as this difference seeks to equalize.
As the sun heats Earth, land absorbs solar radiation more readily than water, which allows it to heat at a much faster rate. Heat radiates out from the planet's surface to warm the atmosphere through a process known as convention. Wind is created when the air above landmasses absorbs heat from the surface until it begins to expand and rise, drawing in heavier, cooler air from over the oceans to take its place. This process is reversed at night when air above the land cools more rapidly than air above the planet's oceans.
Wind patterns and atmospheric currents are formed on a global scale because air near the planet's equator is heated more rapidly than the air found in polar regions. Global wind patterns include trade winds as well the jet stream, a river of air that forms a boundary between polar air masses and the warmer air found closer to the equator.