Climate Zones World Climate Zones Map ES10 Deirdre Scholar earthobservatory.nasa.gov Biomes Climate vs. Weather Climate: long-term average (decades - centuries) of weather (temperature & precipitation) Weather: short term (hours days) atmospheric conditions 1) temperature, 2) moisture, 3) pressure, 4) wind Is Climate stable? Does it vary over time? Climate is variable seasons Climate is variable climate events (hurricanes, ENSO) Summer/winter comparison in Iceland courtesy www.flickr.com/photos/gunnarfreyr Hurricane Sandy image courtesy of earthobservatory.nasa.gov 1
Climate varies over Earth s history (Graph shows latter half of Pleistocene: past 1.6 m.y.) Climographs At least 3 decades of temperature & precipitation data Monthly averages Image courtesy of Pearson Publishing Image courtesy: southhill.vsb.bc.ca What controls locations of climate zones (& biomes)? 1. Latitude & Insolation 2. Atmospheric Circulation & Ocean Circulation 3. Topography 4. Proximity to water (Maritime & Continental climates) 5. Elevation 6. Storms Image Source: www.southhill.vsb.bc.ca 1) Latitude & Insolation Angle of incidence: angle sun s rays strike E s surface. Insolation: Incoming solar radiation Tropical: concentrated Polar: spread out Snow & Ice 80-85% Clouds 70-90% Water (low sun angle) 50-80% Sand 20-30% Forest 5-10% Water (high sun angle) 5% Dark Soil 3% Albedo (reflectivity) Source: 2
Absorption: opposite of Reflection 2) Atmospheric & Ocean Circulation Hadley Cells Rising air @ equator, Inter-tropical Convergence Zone/ITCZ (Doldrums); evaporative cooling Trade Winds Solar radiation absorption From www.physicalgeography.net Seasons Cause: Tilt of Earth s axis (23.5) changes location of concentrated insolation Seasonal Shifts in Global Atmospheric Circulation www.classzone.com Image courtesy: southhill.vsb.bc.ca Why are the hottest places on earth not in the tropics? Adiabatic Cooling & Warming Warm air rises---> air expands & cools Cool air sinks air compresses & warms No heat is added or removed (adiabatic) Descending air @ 30 N & S latitudes Compressional heating; high pressure & clear skies 3
Coriolis Effect Caused by Earth s rotation Unattached moving objects (atmosphere & oceans) follow curved paths right in northern hemisphere; left in southern hemisphere Ocean gyres Movement driven by Coriolis N. Hem. Clockwise; S. Hem. counterclockwise Gulf Stream currents are warm on east coasts cold along west coasts of continents Ocean Currents influence climates on east & west coasts of continents @ same latitude Chile is cooler and drier Brazil is tropical 3) Topography Orographic (mountain) Effect & Rain Shadows Mountains - air masses rise, cool, H 2 O condenses Rain on windward side of mountains Dry on leeward side of mountains currents are warm on east coasts cold along west coasts of continents Topographic Barriers/mountains Rain on windward side of mountains Dry on leeward side of mountains Different climates on same island Rain Shadows in California 4 mountain ranges between the SC and Death Valley Death Valley Hottest, driest place in North America 4
4) Proximity to Water Maritime & Continental Climates Hottest and coldest places on Earth are inland/ continental interiors Antarctica -128.6 F Al Azizivah, Libya 136 F Death Valley, CA 134.1 F 5) Elevation; Mountain Climates Controlled by elevation & angle of sun exposure NOT latitude Sharp vertical zonation of temperature (and vegetation) http://en.wikipedia.org/wiki/file:deathvalleydunes4.jpg Climate Zones ES10 Deirdre Scholar Review questions for Climate Zones Lecture 1. Describe the main differences between weather and climate--what controls them? 2. Define angle of incidence, insolation and albedo. What is the relationship between latitude (distance from equator), angle of incidence, insolation and average temperatures? 3. Which surfaces have high albedo, which have low albedo? 4. What kinds of climate should we expect at the equator (0 ), 30 N&S? 5. Why do wind and ocean currents flow in a curved path? Name of effect? 6. What causes seasons? How do seasons change location of rainfall patterns? 7. What temperature patterns exist with ocean currents on east and west coasts of continents? Give an example of how ocean water temps & climates vary at the same latitude & continent along opposite coasts? 8. Orographic Effect & Rainshadows: Why are the eastern facing (leeward) slopes of California s mountain ranges drier than the western facing (windward) slopes? Explain the formation of Death valley s climate. 9. Mountain climates: controlled by? Characteristics? 5