MiscEl: Weather and air

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This page is used to calculate some weather, air and wind releated values.

Functions

Dew point / %RH	Convert between different ways to measure water contents in air
Wind chill factor	Perceived air temperature
Heat index	Perceived discomfort in hot air
Air at altitude	Different average values depending on altitude
Air at pressure	Different values depending on air pressure
Wind turbine power	Estimate power from wind turbines

Input values

Temperature	Actual temperature for calculations
%RH	Relative humidity in percent (Optional)
Dew point	Dew point temperature (Optional)
Wind speed	Actual windspeed
Altitude	High above sea level
Pressure	Air pressure
Rotor Ų	Rotor Ų for wind turbine, used to calculate area of wings

Output values

H2O pressure	Partial pressure from H₂O at specified values
H2O saturation pressure	Pressure for saturated air at specified temperature
%RH	Relative humidity in percent
Dew point	Any surface with a temperature below this value will get wet
Water	Amount of water in the air
Wind chill	Based on heat loss from exposed skin
Heat loss	Heat loss is based on human skin temperature
Heat index	Combines temperature and relative humidity to estimate heat discomfort
Summer simmer index	Combines temperature and relative humidity to estimate heat discomfort (Also called SSI)
Water boils at	Water boils different temperature, depending on air pressure.
Air temperature	Average temperature at selected altitude
Air density	Air density at pressure and temperature
Power	Power in wind, calculated from mowing air mass
Rotor area	Area of roter, the full area is assumed to be sweept by the wind
Area power	Power in wind, calculated from mowing air mass in rotor area
Theoretically max	Theoretically maximum power from wind, this is 59% of the total power (Betz' law)
Power, good design	Estimated power output for a good designed wind turbine
Power, simple design	Estimated power output for a simple designed wind turbine

Hints

Water changes with temperature, why?	Assuming constant pressure, the volume of air will change with temperature
Wind chill 2001	Assumes wind speed is measure in 10 meters height and that body is at ground level. Is based on a human face model
Wind chill 1939	Based on freezing times of a water bottle
Temperature and wind chill	Objects will not be cooled below actual temperature, just cooled faster due to wind chill factor

Other pages

For other sound in air calculations, use the Sound page.