The humidity of the air.
Humidity is a quantity that characterizes the content of water vapor in the Earth’s atmosphere. This is one of the most important characteristics of weather and climate, affecting human, other living organisms and processes.
Humidity is a quantity that characterizes the content of water vapor in the Earth’s atmosphere.
In fact, air is a mixture of gases consisting of oxygen, nitrogen, etc. gases, including water vapor. Water vapor is a small part of the whole mixture of gases.
Humidity is one of the most important characteristics of weather and climate, affecting human, other living organisms and processes.
The main characteristics of moist air are:
– absolute humidity (or density of water vapor in the air).
– relative humidity of air.
The absolute air humidity (f) is the amount of water vapor (in mass units), are actually contained in 1 m3 of air.
In other words, the absolute humidity of air is the density of water vapor in the air.
Commonly used unit of absolute humidity – grams per cubic meter g/m3.
Absolute humidity is determined according to the formula:
f = m / V,
m is the mass of water vapor contained in a certain volume of air
V – volume of air.
The amount of water vapor is measured in units of mass in kilograms or grams. But for ease of determining absolute humidity of air and a small amount of air contained in the water vapor amount of water vapor measured in grams.
Water vapor content at the surface on average is between hundredths of a percent by weight in the polar latitudes and up to 2.6% near the equator.
Relative humidity (φ) is the ratio of the current absolute humidity to the maximum absolute humidity at a given temperature.
Relative humidity is usually expressed in percent.
Relative humidity of air – a measure of how far the vapor from saturation.
Relative humidity is the ratio of actual pressure of water vapor contained in the air (i.e. the water vapour partial pressure or vapor pressure) to the saturated vapor pressure at a given temperature, expressed as a percentage
Relative humidity of air is determined by the formula:
φ = f / fmax · 100 %,
f density of water vapor (absolute humidity) at a given temperature in g/m3
fmax is the density of saturated steam (maximum absolute humidity) at a given temperature in g/m3.
Relative humidity is very high in the Equatorial zone (average to 85 % and more) as well as in polar latitudes and in the winter inside the continents in the middle latitudes. In summer, high relative humidity is characterized by monsoon areas. Low values of relative humidity are observed in subtropical and tropical deserts in the winter and in the monsoon regions (50% and below).
The maximum absolute humidity for different temperatures is:
|Temperature t, °C||-30||-20||-10||0||10||20||30|
|The maximum fmax absolute humidity (g/m3)||0,330||0,880||2,156||4,868||9,356||27,148||30,078|
|Temperature t, °C||40||50||60||70||80||90||100|
|The maximum fmax absolute humidity (g/m3)||50,672||82,257||129,020||196,213||290,017||417,935||588,208|
The maximum absolute humidity shows maximum possible (limiting) the amount of water vapor that can be contained in a unit volume of air at a certain temperature.
The table shows that at a higher temperature, air can contain more water vapor than at low.
The temperature at which airborne water vapor reaches the state of saturation is called the dew point. The relative humidity of the gas is 100 %. With the further influx of water vapor and cooling of the air condensate appears.
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