WEATHER
INGREDIENTS
focus on moisture in the atmosphere
While you were decoding the station plots you might have wondered what the dew point temperature was. The dew point temperature helps us track moisture in the atmosphere. The definition of the dew point is "the temperature to which the air could be cooled before precipitation would form". Put in another way, clouds form when air is cooled to its dewpoint, or when the air reaches saturation.
When the air temperature and dew point temperature are close together, there is alot of moisture in the air and it is probably very humid outside. When they are far apart, it is very dry. When they are equal, the relative humidity is 100%, clouds will form (if they haven't already) and it will start to rain or snow, or maybe just be very foggy.
The potential for cloud formation (and precipitation) depends on the amount of water vapor in the atmosphere. As rising air cools, its relative humidity increases. Eventually the relative humidity becomes 100%, the temperature equals the dew point, and a cloud forms. Meteorologists always check the dew points when making a forecast. You wouldn't forecast rain if the dewpoints were decreasing and dry air was moving into a region.
