Properties of Air Flashcards
Properties of the air
- Density
- Temperature
- Pressure
- Humidity
Density
- Mass of air molecules within
a specified volume - Thickness of air
-Density is expressed as kg/m3 or g/m3.
-In ISA at mean sea level the air density
is 1.225 kg/m3 or 1225 g/m3
-Density can also be expressed as DENSITY ALTITUDE
Density in relation with temperature
TEMPERATURE INCREASES = DENSITY DECREASES. AIR RISES
TEMPERATURE DECREASES = DENSITY INCREASES. AIR SINKS
Density in relation to pressure
When PRESSURE decreases, air expands
and DENSITY decreases. AIR RISES
When PRESSURE increases, air becomes compressed, and DENSITY increases. AIR SINKS
Density in relation with humidity
When HUMIDITY decreases, more air molecules in the volume and less water vapor, DENSITY INCREASES
When HUMIDITY increases, Air molecules expand in the volume, water vapor enters and fills the gap, DENSITY DECREASES
Temperature
Is a measure of how HOT or COLD the air is.
- CELSIUS
- FAHRENHEIT
International Standard Atmosphere (ISA)
Sea Level Temperature = 15 ˚C
Lapse Rate = 2 ˚C / 1000 FT
Types of Heating of Earth and Atmosphere
- Solar radiation
- Terrestrial radiation
- Conduction
- Convection
- Advection
- Turbulence
Solar Radiation
majority of solar radiation passes straight through the atmosphere to be absorbed by the earth.
Terrestrial Radiation
The atmosphere is heated primarily
by TERRESTRIAL RADIATION
Conduction
Conduction is the transfer of heat by direct physical contact
This happens close to the surface
Convection
the VERTICAL transfer of heat, both upwards and downwards
Advection
the HORIZONTAL transfer of heat
Turbulence
the chaotic interference / mixing between airflows
Isobar
Line that connect areas of
EQUAL PRESSURE
HUMIDITY
Amount of water vapor in the air
– Water vapour: water in gaseous form (invisible)
– Water droplets: water in liquid form (visible
Latent heat
heat or energy that is absorbed or released during a phase change of a substance
Relative humidity
- is the most common indicator of humidity
- how much water vapor is in the air compared to how much it can hold
Dewpoint
The temperature to which air must be cooled for it to become saturated
Unsaturated Air
air that is not holding as much water vapor as possible
Cloud base formula
1,000 X TEMPERATURE – DEW POINT /
2.5 ˚C (or 4.4 ˚F)
Saturated Air
air that contains the maximum amount of water vapor it can hold
