Why does a drop in air pressure indicate the coming of cloudy weather and a rise in air pressure indicate clear weather?
What will be an ideal response?
Answer: First of all, warm air is associated with high atmospheric pressure and cold air is associated with low atmospheric pressure. As air rises it cools by expansion. As air sinks it warms by compression. As air sinks and warms, its capacity for holding water vapor increases. Because more water vapor molecules are required to saturate a warmer air parcel, sinking air inhibits the formation of clouds. On the other hand, as rising air cools, its capacity for holding water vapor decreases. Because less water vapor is required to saturate the colder air, rising air enhances cloud formation. Cloudy skies are thus due to rising (cooling) air and low pressure, while clear skies may be the result of sinking (warming) air and high pressure.
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Indicate whether the statement is true or false
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