Why is the dew point important?
Posted November 2, 2016
Updated November 3, 2016
How is the dew point used for weather forecasting?
Mike Moss: Dew point is of great interest to meteorologists because it is a very basic measure of the state of the atmosphere in terms of how much water vapor is present. Unlike relative humidity, which depends on both temperature and the amount of water vapor (so that the relative humidity can change even if the amount of water vapor remains the same), dew point is directly related to the amount of water vapor and will increase if there is more water vapor and vice versa.
Furthermore, dew point can provide a fairly direct sense of how comfortable or uncomfortable warm air will feel, since we tend to not notice humidity very much on a warm day when the dew point is in the 50s or lower, while dew points in the 60s tend to feel a little more humid, those near 70 feel quite muggy, and upper 70s and above can seem oppressively humid.
Dew point can also give us a reasonable starting point for estimating low temperatures the following day, as under certain conditions the low will end up pretty close to the dew point at the time of maximum temperature the day before. We can also use projections of dew point temperature to aid in forecasting the formation of fog or dew, and in estimating the height of cumulus or stratocumulus cloud bases for aviation weather forecasts. Finally, higher dew points through the lower atmosphere (especially those above 60 degrees or so) can help to support more numerous and/or intense thunderstorms when other factors favor their formation.
I'm probably leaving out some important applications, but that should give you a general idea of why we find dew point so useful.
Full question from Farhan Ahmed: Why might meteorologists be interested in dew point? From science class...
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