Geographical Controls of Weather and Climate

• Latitude

• Continentality

• Altitude

• Topography– Terrain dimensions– Relief– Slope and aspect

Latitude

• Net radiation and temperature decrease as latitude increases

• Elevation of treeline/snowline decreases poleward

• Belt of alpine vegetation and permanent snow and ice are lower on mountains at high latitude versus the tropics

Day Length

Whiteman (2000)

Altitude Angle of the Sun

Whiteman (2000)

Continentality

• Arises from differences in heat capacity and heat conduction of soils vs. water– Water able to store more heat– Soils less

• Degree of continentality expressed by annual range of mean monthly temperature

Temperature: Annual vs. Diurnal

Java Austria

Barry (1992)

Altitude• Distribution of state variables (p,,T,u) depends strongly on height

in free atmosphere and as function of terrain height• Vapor pressure of water and radiation also vary strongly with height

Whiteman (2000)

Hydrostatic Atmosphere

• dp/dz = - g

• p= RT

• ln(pB/pT )=RgTave (zT – zB )zB

pB

pT zT

Tave

Whiteman (2000)

Standard AtmosphereHeight (m) Pressure(mb) Temperature(

C)Density(kg/m3)

0 1013 15 1.22

1000 900 9 1.11

2000 795 2 1.05

3000 701 -5 .909

4000 616 -11 .819

5000 540 -18 .78

Actual vs. Standard Atmosphere

Whiteman (2000)

Vapor Pressure• Vapor pressure (e)- partial

pressure of water vapor– Absolute measure of water

content in atmosphere

• Saturation vapor pressure (es)- saturation vapor pressure– Maximum amount of water vapor

atmosphere can hold for given temperature

e:(mb)3.3

11

14.5

(m)3776

1000

0

Mt. Fuji

Impacts of Vapor Pressure

• Higher vapor pressure reduces transmission of IR• Refracts/absorbs solar radiation• Flux of water vapor proportional to (es –e); so, for

given temperature, lower vapor pressure increases evaporation

• Compared to free air, vapor pressure is higher usually near mountain– Reduces transmission of IR, which may increase temperature– Lowers condensation level– lowers drying power, i.e., ability to transfer water from

clothing/plants into atmosphere

Physiological Factors of Altitude: Oxygen Deficiency

• Proportion of Oxygen in atmosphere- 21%• Partial pressure of Oxygen decreases with height in proportion to other gases• Lungs saturated with water vapor; reduces available oxygen• Oxygen in lungs: (ambient pressure – saturation water vapor pressure at body temp

(37C) (63 mb)) * .21• Sea level (1013 – 63 ) * .21 = 200 mb; 5000 m (540 – 63 ) * .21 = 100 mb• Hypoxia- intolerance to oxygen deficiency

– Humans can tolerate half sea level value indefinitely– Symptoms significant above 3000 m (133 mb)

• Standard Atmosphere varies with latitude (4000 m roughly 630 mb equatorward of 30o; 593 mb (winter)-616 mb (summer) at 60o

• Cyclone could drop pressure 10-20 mb; equivalent to several hundred meters in elevation

• Grover (1974); Man living at high altitudes. Arctic and Alpine Environments.

Inspired Oxygen as a Function of Elevation

200mb

100mbGrover (1974)