Relative Humidity

`rh = W / W_s `

`(W)"Actual Vapor Density"`

`(WS)"Saturated Vapor Density"`

The Math / Science

Relative humidity is the amount of moisture in the air compared to what the air can "hold" at that temperature. Relative Humidity is also a common index regarding human comfort maintaining a normal temperature. Human comfort is ideally near 50% RH, while RD less than 30% is dry air and RD greater than 70% is considered humid.

When the air can't "hold" all the moisture,then it condenses as dew.

The formula for relative humidity is:

rh = W/Ws

where:

rh is the relative humidity converted to a percentage
W is the actual density of the vapor
Ws is the saturation density of the air.

Weather (Meteorology) Calculators

Heat Index: Approximates the heat index based on the temperature and relative humidity
Canadian Humidity Index (HUMIDEX): Computes the Canadian Humidity Index (HUMIDEX) based on the dry-bulb ambient temperature and the dew-point temperature.
Australian Apparent Temperature (AT): Computes the apparent temperature based on the dry ambient temperature, the relative humidity and the wind speed at ten meters.
Relative Humidity: Computes the relative humidity based on the actual density of vapor and the saturated density.
Dew Point from Relative Humidity: Computes the dew point based on the relative humidity and ambient temperature.
Summer Simmer Index: Computes the Summer Simmer Index based on the air temperature and relative humidity.
Wind Chill Index (North America): Computes the wind chill index based on the air temperature and the velocity of the wind.
Wet-Bulb Globe Temperature (WBGT): Computes the wet-bulb globe temperature index based on dry-bulb (air) temperature, globe thermometer temperature and the wet-bulb temperature.
Humature Index: Estimates the humidity index based on the temperature and dew point.
Antoine Equation: Computes the apparent vapor pressure of pure substances based on temperature and coefficients for the substance.
Barometric Formula (Tropospheric) calculator computes the normal barometric pressure based on the altitude (h) using the Exponential Atmosphere formula.
Planetary Temperature: Estimates a planet's temperature based on the luminosity of its star, distance to the star, average albedo and infrared optical depth of atmosphere.
Snow Water Equivalent (SWE): Computes the volume of liquid water contained in rain or snow pack defined by area, depth and snow type or rain.

References

http://hyperphysics.phy-astr.gsu.edu/hbase/Kinetic/watvap.html