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To understand why low pressure produces cloudy weather, there are several properties of air that we first need to understand:
1) Air is a mixture of gases, including water vapor. Clouds form when water vapor (gas) condenses into (liquid) water droplets.
2) Cold air can't hold as much water vapor as warm air can. (This is why you see your breath in the winter but not the summer; your warm breath is cooled enough in the winter that some of the water vapor in it condenses into liquid water droplets.)
3) Lowering the pressure of air causes its temperature to decrease. For example, if you let the air out of a tire, you will observe that the escaping air feels cold. (Likewise, compressing a gas raises its temperature; this is why the bottom part of a bicycle pump feels hot after pumping up a tire, for example. Both of these statements are contained in the equation PV=RT, the Ideal Gas Law.)
4)The pressure higher in the atmosphere is lower, because there is less weight of air pushing down. This is why people talk about the air being "thin" on mountaintops.
5)A low pressure system is a region of rising air.
--> So, a low pressure system is cloudy because it is an area of rising air (5), which cools as it rises because as a result of the pressure being lower higher in the sky (4), the temperature goes down (3). Since the temperature goes down, the water vapor in the air (1) condenses into water droplets (2), making clouds.
This is also why most clouds have flat bottoms--the bottom of the cloud marks the altitude that the pressure is low enough that the temperature is low enough that the water vapor can condense out into clouds.
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JudyHigh pressure areas are associated with descending air, which inhibits the formation of clouds. As the air sinks, it warms and dries out, leading to lower humidity levels that are not conducive to cloud formation. Additionally, the lack of rising motion in high pressure systems prevents the lifting of air to condensation levels, further limiting cloud development.
The reason why areas of high PRESSURE have fewer clouds than areas of low pressure is because areas of high pressure suppress air, while areas of low pressure force air upward. Because areas of high pressure suppress air, water vapor cannot rise and condense into clouds as easily.
Cold, sinking air aloft is compressed and heated as it sinks in areas of high pressure. This causes an elevated temperature inversion. An elevated temperature inversion occurs when a layer of warm air resides over a layer cooler air (at the surface) thereby restricting the vertical movement of air. The vertical movement of air is necessary for cloud development. This is why you see very few, if any, clouds in areas of high pressure.
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When air moves upward to areas of less pressure what often forms?
fog
Do clouds rise in the center of a low pressure or high pressure area?
Clouds typically form in low pressure areas where air is rising and cooling, causing condensation to occur. In high pressure areas, air sinks and warms, which inhibits cloud formation.
Do clouds form during high or low pressure system?
Clouds are more likely to form during low pressure systems. As air rises in a low pressure system, it cools and condenses to form clouds and eventually precipitation. In high pressure systems, air sinks and inhibits cloud formation.
Are cumulonimbus clouds low or high pressure?
Cumulonimbus clouds are typically associated with low pressure systems. These clouds are tall and vertical, often reaching high into the atmosphere, which is characteristic of regions with lower atmospheric pressure.
Does it rain in low pressure areas or high pressure areas?
It is more likely to rain in low pressure areas because low pressure systems often bring rising air, which can cool and condense to form clouds and precipitation. High pressure systems generally bring more stable weather with sinking air, leading to clear skies and less chance of rain.
