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Climate_Change BIO 350

Climate_Change BIO 350 - Climate Change I Climate A Climate...

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Climate Change I Climate A Climate vs. weather 1. Climate is the long term pattern of temperature and precipitation for a given area a) Temperature measurements include average yearly temperature as well as extreme high and low temps. b) Precipitation is any form of water that forms in the atmosphere & falls out of the sky (rain, snow, fog, etc.) 2. Weather is the condition of the atmosphere at a particular place and time a) Weather conditions are determined by atmospheric temperature & pressure, humidity, wind, cloudiness, & precipitation b) Weather is always changing rapidly (minute-by-minute, day-by-day) B Factors that affect climate 1. Solar Energy a) The sun is the main source of heat for the surface of the planet b) Solar output ranged between 1368 watts/m 2 and 1365 watts/m 2 over the past 30 years c) Variations in solar output affect temperatures i) Recent data suggest a possible increase of 0.1 – 0.6% over the past 300 years or a 0.05% increase per decade over the past 30 years ii) How much this increase in solar output has contributed to the current warming trend is unclear due to many factors d) Approximately 31% of solar radiation is reflected by the atmosphere, clouds and surface features (mostly snow & ice) e) Of the remaining 69%, 17% is absorbed directly by the atmosphere, 3% by clouds, & 49% is absorbed at ground level f) The amount of solar energy absorbed at the surface is affected by latitude and the tilt of the earth. i) Energy is most intense near the equator because energy is nearly perpendicular to the surface (more concentrated) ii) Energy is less intense at higher latitudes because the energy arrives ant an angle (due to the curvature of the earth) and is therefore spread out. (a) Seasonal variation in solar energy is due to the tilt of the earth relative to its orbital plane around the sun. 2. Amount of precipitation a) Depends on 3 related factors i) Amount of water vapor in the atmosphere (a) Warm equatorial areas experience evaporation, esp. over the ocean (b) As warm, moist air rises it cools, allowing vapor to condense and fall as rain ii) Geographic location (a) Eventually cold air sinks at around 30 o N & S (b) The air has lost its moisture already so the underlying areas are arid
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(c) Also, windward coastal areas experience more precipitation than inland areas iii) Topography (a) Mountain ranges can force moist air to higher altitude, forcing precipitation on the windward side (b) The air flowing over the top of the mountains is dry, so the leeward side is more arid (rain shadow effect) 3. Ocean circulation a) Coastal areas have more moderate climates because of water’s capacity to absorb & release heat slowly b) Surface currents transport warm water to cooler latitudes keeping air temperatures elevated c) Eventually surface waters cool & lose water which concentrates salt.
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