Weather experts frequently discuss the term ‘dewpoint,’ but many people may not fully understand what it means. Dewpoint refers to the temperature at which water vapor in the air condenses into tiny droplets, forming dew on surfaces like glasses.
For example, if glasses are stored indoors at 74 degrees and taken outside into air with a 79-degree dewpoint, dew will form on the lenses. A 79-degree dewpoint signals high humidity, such as the 81-degree dewpoint recorded in Memphis today, which is considered oppressively humid.
Conversely, on a pleasant fall day with a dewpoint of 50, glasses stored at 74 degrees are warmer than the air, so no fogging occurs when stepping outdoors. However, if those same glasses are cooled to 42 degrees in a refrigerator and then taken outside into the same weather, fogging can happen.
For more information on humidity and dewpoint, visit NOAA’s educational resources at this link.
Jon Ross Myers is the executive editor and publisher of the Mississippi News Network, Mississippi's largest digital only media company. He can be reached at editor@tippahnews.com
