NBC Action Weather Plus Calculators
Have you ever wondered how relative humidity affects how hot it really feels outside? Confused about what the dew point really is? You can learn all about these and other weather terms with our interactive NBC Action Weather Plus Calculators below.

Related weather definitions from NBC Action Weather Plus:

 • dry bulb temperature – It is simply the air temperature. This term is somewhat outdated since we rarely use thermometers with bulbs anymore. Dry bulb temperatures are measured along with "wet bulb" temperatures and can be used to determine humidity and dewpoint.
 • wet bulb temperature – A regular liquid-in-glass thermometer bulb is covered by a cotton wick and moistened. Air is blown across the moist wick and the bulb is cooled by evaporation. The lowest temperature reached with the bulb wet is the wet bulb temperature. We use it to figure humidity and dewpoint.
 • relative humidity – a percentage of moisture in the air compared to what it can hold at that temperature.
 • dew point – the temperature to which air must be cooled for saturation to occur; the temperature at which dew or frost will form.

What else can the Dew Point tell you?
Dew Point, along with Temperature, can tell you the estimated height of a cloud's base. How? When air rises in a convective current, it cools at the rate of 5.4° F/1,000 ft, and its dew point decreases 1° F/1,000 ft. Therefore, the temperature and dew point are converging at 4.4° F/1,000 ft. Since clouds form when the temperature/dew point spread is 0°, you can use that information to estimate the base of a cumulus cloud. Here's how it works: Subtract the surface dew point from the surface temperature to give you the temperature/dew point spread. Then divide that number by 4.4° F. Finally, multiply this result by 1,000 ft. This total will be your estimate of the cloud base's height above ground level (AGL). Try it using the Cloud Base Calculator below!

NBC Action Weather Plus Calculators:
 • Barometric Pressure Conversions
 • Cloud Base Calculator
 • Density Altitude Calculator
 • Dew Point Calculator
 • Fahrenheit / Celsius Conversion
 • Heat Index Calculator 1
 • Heat Index Calculator 2
 • Relative Humidity Calculator
 • Relative Humidity / Dew Point Calculator
 • Wind Chill Calculator
 • Wind Velocity

Learn more weather terminology here.