Soils and Hydrology Chapter 10

What is Humidity?

THE AMOUNT OF WATER VAPOR IN THE AIR

How can you increase the moisture capacity of Air?

increase its temperature. High heat=high humidity

RELATIVE HUMIDITY

: the amount of moisture in an air parcel
compared to what the parcel could hold at that temperature –
expressed as a %

What force causes dew formation?

Relative humidity in the mornings is low. This causes the air to saturate and produce…

DEW POINT:

the temperature at which air becomes saturated, leading
to condensation.

Latent heat:

The heat energy that is absorbed or released in the phase change of
water and is stored in one of the three physical states (ice, liquid, vapor)

What is the primary driver of weather conditions?

Latent heat exchanged between water

Stability (in terms of air)

how much the air is moving around vertically

Lifting condensation level (LCL)

the altitude at
which an air parcel
becomes saturated
(relative humidity reaches
100%) as it rises and
cools, leading to cloud
formation.

What leads to precipitation?

results from the growth of cloud

droplets through collision and coalescence,

leading to raindrop formation and eventual fall to

the ground

Four types of atmospheric lifting mechanisms:

1.Convergent uplift

2.Convectional uplift

3.Orographic uplift

4.Frontal uplift

CONVERGENT UPLIFT:

results from air flowing from different directions

into a low-pressure area, forcing air to rise and form clouds

CONVECTIONAL UPLIFT:

occurs when a parcel of air is heated relative to
to the surrounding air (think boiling water)

OROGRAPHIC UPLIFT:

results from a topographic barrier to migrating air

masses (think mountains)

FRONTAL UPLIFT:

results from the collision of air masses with different

temperatures, where warm air is forced to rise over a denser, advancing

cold air mass. Hot hits Cold

ADIABATIC =

warming or cooling of a parcel of air by expansion or compression

• Rising air cools by expansion

• Sinking air warms by compression