meterolgy ( chapter 7 > required skills and knowledge )

Saturated air

Contains maximum amount of water vapour that is possible at a given temperate / air pressure

The main sources of atmospheric humidity is

1. Ocean

2. Seas

3. Lakes

4. Rivers

Without water vapour there would be no …

Weather

Relative humidity changes with

1. amount of water vapour present in the air ( added by evaporation from bodies of water )

2. The temperature of the air ( it’s capacity to hold water vapour )

Condensation is

Is the phase change from water vapour to liquid water. Occurs when contact with a liquid or solid surface.

Evaporation is

Is the phase change from liquid water to water vapour

Sublimation is

Is a phase change from solid ice water to water vapour

Deposition is

The change from water vapour to solid ice, without passing through a liquid

Freezing ( fusion ) is

The phrase change from liquid water to solid ice. Beings to occur when temperature of the liquid falls below its freezing point

Melting is

The phase change from solid to ice liquid water. Begins to occur when the melting point is reached

Latent heat is

Realised or absorbed by a body during a state of matter change. Without changing its temperature

Evaporation can occur whenever

The air is unsaturated

Condensation creates

Visible liquid water in the atmosphere ( cloud or fog )

For condensation to occur the air must be

Saturated and then cooled below its dew point

Supercooled water is

Is a liquid water existing at a temperature below freezing point

Latent heat during melting and evaporation

1. Latent heat is absorbed from the surroundings

2. The gas state has the highest latent heat content

Latent heat during condensation or freezing

1. Latent heat is released to the surroundings

Melting occurs when

Snow falls into the warmer lower layers

Supercooled condensation occurs when

Droplets can freeze if they come into contact with an aircraft surface

Sublimation commonly occurs

Over snow

Deposition commonly occurs when

Ice crystals grow within regions of clouds where the ambient vapour pressure falls between the saturation vapour pressure around the water and the lower saturation vapour pressure around the ice