4 Temperature and Precipitation Climate is an area’s long-term pattern of weatherThe two main characteristics of climate are Temperature and PrecipitationOther characteristics are the number of days and hours of sunlight; direction, speed and steadiness of the wind; and occurrence of severe weather
5 Average Temperature can be misleading. Annual Temperature range is the difference between the average temperature of the warmest month and the average temperature of the coldest monthAverage Temperature can be misleading.e.g. Average temperature for Beijing, China, and Valdivia, Chile are the same. However, Beijing goes to extremes from –4°C to 26°C while Valdivia ranges from 7°C to 16°C.
6 Average Precipitation can also be misleading, one place may get all its rain during a few months (Bombay, India) and another over the entire year (Mobile, Alabama)
7 Climate ControlsLatitude – generally colder toward poles with little precipitationElevation – higher the cooler and drierNearby Water – Temperature range small mild climate if downwind more moistureOcean Currents – warm currents warm nearby coastsTopography – leeward side warmer than windward, windward side may be wetter, can act as a barrier to air masses.
8 Vegetation – will effect insulation, releases water vapor Prevailing Winds – blow from a hot or cold region, blow from water or landVegetation – will effect insulation, releases water vaporSome climate controls are more important than others depending on location.e.g. London, England is pretty far north, however the warm ocean currents keep its climate mild.
11 Polar Climates Very cold in winter with little or no daylight The sun strikes at such a low angle in summer it provides little solar energyMuch of the light is reflected back to space by snow and iceTundra are located in Polar Climates, they are very cold with little precipitationIce caps are another sub climate in polar climates
12 Dry Climates – cover 30% of Earth Occur in regions that lose more water due to evaporation than it receives from rainDry climates often exist on leeward sides of mountain ranges and where air sinks in the horse latitudeSemi-arid climates are not as dry as deserts and are often home to dense grasses. (Great Plains of the US)
13 Humid Tropical Climates Hot year round – near the equator…ITCZTwo sub climates…Tropical wet & Tropical wet and dry – wet summers, dry winters.
14 Most mid-latitude Climate – There are 2 of them, one with mild winters, the other with severe winters.Mild winter – There are 3 typesHumid subtropical – SE U.S. – Hot muggy summer, mild wintersMarine west coast – west coast of Canada and NW U.S. – cool summers, mild wintersMediterranean – west coast of SW U.S. & the Mediterranean Sea – dry summers – wet winters with mild temperatures
15 Highlands – mountainous regions in which multiple climates exist Severe winters – snow often covers ground in winter but summers are warm – subclimates humid continental and the subarcticHumid continental – found in the interior of continents and on eastern coasts including the N U.S. east of the great plains – winters very cold and summers very warmSubarctic – near poles – short summersHighlands – mountainous regions in which multiple climates exist
18 Cause of Climate Change Global mean temperature during the last Ice Age was only 5°C cooler than today’s global mean temperatureIf an increase in cloud or ice cover causes more sunlight to be reflected out to space, Earth may cool
19 There is thought to be 4 basic causes for climate change Earth’s Motion – shape of its orbit, tilt of its axis varies between 22.1° to 24.5° in a 41,000 year periodThese changes affect sun intensity which may allow ice to grow on surfacePlate tectonics – moving of the continentse.g. Greenland is thought to once have a warmer climate (close to equator) because of tropic fossils found in Greenland
20 Sunspots – the more sunspots the more energy given off by the sun Volcanoes – increase dust, clouds and CO2 – may add to warming the atmosphere like what happened during the cretaceous period.
21 Human Effects on Climate Due to deforestation and fossil fuel burning CO2 in the atmosphere has increased since the 1800’sComputer models not accurate because of all the variables
22 Measuring Climate Change Scientists use sea floor sediments, glacier samples and tree rings to study the past climates