Atmospheric ProcessesAtmospheric Processes

1.1. Air MovementsAir Movements

2.2. Surface WindsSurface Winds

3.3. Pressure SystemsPressure Systemsa)a) Characteristics of high & low pressure Characteristics of high & low pressure

systemssystems

b)b) Influence of high & low pressure systems on Influence of high & low pressure systems on weather patternsweather patterns

4.4. Air MassesAir Masses

What if….What if….

The earth was not tilted 23.5° on its axis?The earth was not tilted 23.5° on its axis?

It did not rotate once every 24 hours?It did not rotate once every 24 hours?

It did not orbit the sun?It did not orbit the sun?

1.Hadley cell - Low latitude air movement toward the equator that with heating, rises vertically, with poleward movement in the upper atmosphere. This forms a convection cell that dominates tropical and sub-tropical climates.

2.Ferrel cell - A mid-latitude mean atmospheric circulation cell for weather named by Ferrel in the 19th century. In this cell the air flows pole-ward and eastward near the surface and equator-ward and westward at higher levels.

3.Polar cell - Air rises, diverges, and travels toward the poles. Once over the poles, the air sinks, forming the polar highs. At the surface air diverges outward from the polar highs. Surface winds in the polar cell are easterly (polar easterlies).

Between each of these circulation cells are bands of high and low pressure at the surface. The high pressure band is located about 30° N/S latitude and at each pole. Low pressure bands are found at the equator and 50°-60° N/S.

Air Movements

Surface WindsSurface WindsAir moves from HIGH to LOW pressure – variable speed and direction but have an overall global pattern

RoaringForties DoldrumsHorse

Latitudes

Remember – Coriolis Effect – these winds are deflected

Atmospheric ProcessesAtmospheric Processes

1.1. Air MovementsAir Movements

2.2. Surface WindsSurface Winds

3.3. Pressure SystemsPressure Systemsa)a) Characteristics of high & low pressure Characteristics of high & low pressure

systemssystems

b)b) Influence of high & low pressure systems on Influence of high & low pressure systems on weather patternsweather patterns

4.4. Air MassesAir Masses

Pressure Systems

Atmospheric pressure systems are areas of the atmosphere with relatively high or low barometric (air) pressure

Surface atmospheric pressure is shown on synoptic charts as isobars

Isobars join areas of equal pressure – like contour lines join areas of equal height

Pressure Systems

1. Define Atmospheric Pressure Systems

2. Explain the characteristics of High Pressure Systems, include:

a) Alternative name

b) Description

c) Weather conditions (winter/summer/sky/pressure gradient)

d) Include diagram to show air movements in N & S hemisphere

3. Repeat for Low Pressure Systems

source abbreviation

English CUT (coordinated universal time)

French TUC (temps universel coordonné)

compromise UTC (not an acronym, English backronym = Universal Time, Coordinated)

UTC – Stands for….