ABC Action News Weather 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 weather calculators below.
Relative Humidity /
Dew Point Calculator
(using Dry Bulb-Wet Bulb Temperatures) |
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Related weather definitions from ABC Action News:
• 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somewhat outdated since we rarely use thermometers with bulbs anymore.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!
ABC Action News Weather 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.
