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Weather Variable
Wind and Air pressure
Question | Answer |
---|---|
Air Pressure | The pressure caused by the weight of the atmosphere. It applies a force equal in all directions. |
Wind | The movement of air, from high pressure to low pressure. Winds are created by uneven heat distribution at Earth’ surface and modified by the rotation of Earth (Coriolis Effect). Creating air pressure differences (high and low). |
High Pressure System | Winds move clockwise and out. Characteristics: High density, cold, sinking air, no clouds. Cold air (molecules) contract and become denser, creating areas of high pressure. |
Low Pressure System | Winds move counterclockwise and in. Characteristics: Low density, warm, rising air, clouds (stormy weather). Warm air (molecules) expands and becomes less dense, creating areas of low pressure. |
Coriolis effect | The wind is deflected (curved) to the right caused by the rotation of the Earth. |
Jet Stream | A current of fast moving air found in the upper levels of the atmosphere (6-9 miles above earth’s surface). Moves from West to East across the United States. |
Local Winds | Named from the direction the come from (origin) **The land heats and cools more rapidly than the sea. Water retains heat longer than land, and also takes longer to heat and cool. This causes differences between the land and the sea. |
Sea Breeze (Day) | The breeze that blows from the sea toward the land during the day. Caused by air rising over the warmer land and is replaced by the cooler air sinking above the sea. |
Land Breeze (Night) | The breeze that blows from the land toward the sea. Caused by air rising over the warmer sea and is replaced by the cooler air sinking above the land. |
High Specific Heat of water | Slowly releases stored energy from the day during the night making the water warmer than the land. Causes Land Breeze. |
Wind Chill | The cooling effect of wind and temperature combined. The higher the wind, the cooler it gets. |
Isotherms | Lines on a weather map of equal temperature. They help us identify both warm and cold air masses. |
Isobars | Lines on a weather map of equal pressure. They help us identify areas of high and low pressure. |
How do winds blow? | Wind blows from areas of high pressure to areas of low pressure. The strength of the wind is determined by changes in the pressure gradient. A large change in pressure over a short distance would indicate strong winds (isobars that are close together). |
Anemometer | Measures wind speed. |
Barometer | Measures air pressure |
Hydrometer | Measures the specific gravity (relative density) of liquids. |