What is dewpoint? Meteorologists explain the concept

Meteorologists often mention the dewpoint, but many people may not understand what it actually means. It refers to the temperature at which air becomes saturated with moisture, causing water droplets to condense. This is the reason glasses fog up when taken outside on a humid day.

For example, if sunglasses are stored indoors at 74 degrees and then taken outside into air with a dewpoint of 79 degrees, dew will form on the lenses. A dewpoint of 79 degrees indicates oppressively humid conditions. In Memphis, the dewpoint reached 81 degrees today, according to the National Weather Service.

On a pleasant fall day with a dewpoint of 50, glasses stored at 74 degrees won’t fog when brought outside. However, if those same glasses are cooled to 42 degrees in a fridge and then taken outside, fogging can occur even in cooler conditions. Understanding dewpoint helps explain these everyday weather phenomena.

Additional information about humidity and dewpoint can be found on NOAA’s education page.

Source: Original Article