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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Maximum Temperature Southern Peruvian Andes (February)
Maximum Temperature Yucatan Peninsula (Annual)
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