Key Idea #15 The warming of the Earth by the sun produces winds and ocean currents.

What causes winds? http://www.weatherquestions.com/wind.jpg

Air will rise if it is warmer than the surrounding air. The upward movement of warm air and the downward movement of cool air form convection currents. If cool air is present, warm air will rise to great heights and eventually cool. Cool air holds less water vapor than warm air.

Local Winds blow over short distances. form when no winds are blowing from farther away. are caused by the unequal heating of the Earth’s surface within a small area. Sea (Lake) Breeze Land Breeze

Sea (Lake) Breeze Unequal heating often occurs on land that is next to a large body of water. Land heats up more quickly than water. The warmer air over the land expands and rises, creating a low pressure area. Cooler air blows inland from the water and moves underneath the warmer air creating a wind known as a sea or lake breeze.

Land Breeze At night land cools more quickly than water, so the air over the land becomes cooler than the air over the water. As the warmer air over the water rises, cooler air moves from the land to take its place. This flow of air from land to a body of water is called a land breeze.

Uneven Heating of the Earth

Global Winds are the movement of air between the equator and the poles caused by the unequal heating of the Earth’s surface. blow from specific directions over long distances.

Coriolis Effect is the way Earth’s rotation makes winds curve. In the Northern Hemisphere all global winds gradually turn to the right. In the Southern Hemisphere all global winds gradually turn to the left.

An ocean current is the movement of ocean water. made up of hot or cold water. Note: The movement of ocean water is similar to the movement of warm and cold air in the atmosphere.

Convection currents move warm water through the oceans. Convection in oceans occur because the ocean waters heat up becoming less dense. The warm water moves above the cooler water, and give off its heat to the surrounding environment. As the water cools, it begins to sink, and the process begins again. Convection results in the continual circulation of ocean water on a global scale.

FYI: How is Wind Measured? Wind speed is measured using an anemometer. The force of the wind causes the cups to spin on an axle which activates a speedometer. Wind direction is measured using a wind vane. The arrow points in the direction the wind is blowing from.

FYI: Beaufort Wind Scale