ANNUAL CYCLE OF AIR TEMPERATURE

Factors: Insolation, Latitude, Surface type, Coast/Interior, Elevation

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GLOBAL PATTERNS OF AIR TEMPERATURE

http://climate.geog.udel.edu/~climate/html_pages/ghcn_T_clim.ann2.html

Willmott and Maatsura Air Temperature interpolation:

Figure 3.16 (Page 79) Global mean monthly temperature for January and July

GLOBAL PATTERNS OF AIR TEMPERATURE

1. Temperatures decrease from equator to poles2. Land masses in subartic and artic regions have extremely low

temperatures in winter3. Temperatures in equatorial regions change little from January

to July4. Large shift of isotherms (north-south) between January and

July over continents in midlatitudes and subartic regions Winter: equatorward Summer: poleward5. Areas of perpetual ice and snow (Greenland, Antarctica) are

always intensely cold

ANNUAL RANGE OF AIR TEMPERATURES (Figure 3.14)

ANNUAL RANGE = TEMP(JAN) – TEMP(JULY)

1. Annual range increases with latitude (especially Northern Hemisphere)

2. Greatest ranges: subartic and arctic regions (North America and Asia)

3. Moderate ranges: tropical zone, near tropics of Cancer and Capricorn

4. Annual range over ocean is less than over land5. Very small over oceans in the tropical region

GLOBAL WARMING AND THE GREENHOUSE EFFECT

Our planet temperature is warming significantly due to human activities? OR

Last few years warming is part of a natural global cycle?

Last years were very warm:

1998 : The warmest year on record (1850-2000) The warmest year of past thousand, based on tree rings

2002: Second warmest year2001: Third warmest year

Is this warming an effect of human activity?

GLOBAL WARMING

GREENHOUSE EFFECT

The atmosphere traps longwave radiation and returns it to the surface

Greenhouse gases (LWR absorbers):CO2, water vapor

Greenhouse liquid:Clouds (tiny water droplets)

GLOBAL WARMING AND COOLING (FACTORS) ( Fig5.23, page 124)

MEAN ANNUAL TEMPERATURE OF EARTH

Mount Pinatubo eruption (Philliphines)

MOUNT PINATUBO ERUPTION (Phillipines)The volcanic eruption of 1991 that cooled the planet

The second largest volcanic eruption of the 20th century (June 1991)

Volcanic activity

Particles and gases (SO2)into stratosphere (aerosols)

Strong winds spread throughout the entirely layer

Aerosols reflect income radiation (cooling effect)

Aerosols : suspension of fine solid or liquid particles (smoke from fires, volcanic activity, air pollution)

GLOBAL DIMMING

The gradual reduction in the amount of global sun radiation at Earth’s surface

Gerald Stanhill (Israel):

Solar Radiation observations: 22% decrease (1950s-1980s)

Beate Liepert (Germany):Similar pattern in Alps

1950-1990 decrease of solar energy:• 9% Antartica•10% USA•30% Rusia

Antartic

Arctic

SEPTEMBER 12, 2001 (USA):

Near-total shutdown of air traffic during the three days

US climate absent from the effect of contrails (visible trails of condensed water vapor).

During this period, an increase in temperature over 1°Cwas observed in some parts of the U.S.

COMBINATION OF GREENHOUSE GAS AND AEROSOL FORCING

Greenhouse warming increasing cloud thickness

increasing cloud thickness

Reduction of surface solar radiation

Cooling surface

However: Atmosphere is still heated trough greenhouse warming

Atmospheric warming and surface cooling might occur at the same time

IPCC: INTERGOVERNMENTAL PANEL ON CLIMATE CHANGE

Role: To assess the latest scientific, technical and socioeconomic literature produced worldwide for understanding the risk of human-induced climate change, its impacts and options for adaptation and mitigation

It’s a scientific intergovernmental body set up by the WMO (World Meteorological Organization) and by the UNEP (United Nations Environment Program)

http://www.ipcc.ch/

Spatial distribution of temperature trends

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