ANNUAL CYCLE OF AIR TEMPERATURE Factors: Insolation, Latitude, Surface type, Coast/Interior, Elevation SS EE

GLOBAL PATTERNS OF AIR TEMPERATURE 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 poles 2.Land masses in subartic and artic regions have extremely low temperatures in winter 3.Temperatures in equatorial regions change little from January to July 4.Large shift of isotherms (north-south) between January and July over continents in midlatitudes and subartic regions Winter: equatorward Summer: poleward 5. 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 land 5.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 ( ) The warmest year of past thousand, based on tree rings 2002: Second warmest year 2001: 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): CO 2, 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 20 th century (June 1991) Volcanic activityParticles and gases (SO 2 ) 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

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°C was observed in some parts of the U.S.

COMBINATION OF GREENHOUSE GAS AND AEROSOL FORCING Greenhouse warming increasing cloud thickness increasing cloud thicknessReduction 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)

Spatial distribution of temperature trends

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