Lecture1ClimateChange

Lecture1ClimateChange - Dr.AlanDoolittle,GaTech

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Dr. Alan Doolittle, Ga Tech cture 1: Understanding the Greenhouse Lecture 1: Understanding the Greenhouse Effect and Anthropogenic Climate Change Reading Assignment – Homework 1 Reading Assignments and Chapter 1 of PVCDROM Dr. Alan Doolittle*
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Dr. Alan Doolittle, Ga Tech Understanding the Green House Effect There is a difference between the reen House Effect a known Green House Effect, a known scientific phenomena , global warming and anthropogenic climate change. All are often used in the popular press as synonymous. Anthropogenic climate change ometimes called Anthropogenic (sometimes called Anthropogenic Global Warming) is the “belief” that mans actions are causing the earths climate to change. The following is from: http://www.esrl.noaa.gov/gmd/infodata/faq_cat-3.html What is the greenhouse effect? The Sun, which is the Earth's only external form of heat, emits solar radiation mainly in the form of shortwave visible and ultraviolet (UV) energy. As this radiation travels toward the Earth, the atmosphere absorbs about 25% f nd bout 5 flected y e louds ack to ace he maining diation avels nimpeded e of it, and about 25% is reflected by the clouds back into space. The remaining radiation travels unimpeded to the Earth and warms its surface. The Earth releases back to space the same amount of energy it has absorbed from the Sun. However, the Earth is much cooler than the Sun, so the energy re-emitted from the Earth's surface is much weaker, in the form of invisible longwave infrared ( IR )rad ia t ion ,some t imesca l ledhea trad t .I fyou stand close to a hot object, but do not touch it, you can feel how the IR radiation heats your skin, although you cannot see the IR rays. Gases that absorb and trap this IR radiation, such as water vapor (H O), carbon dioxide 2 (CO 2 ), methane (CH 4 ) and nitrous oxide (N 2 O) are known as "greenhouse gases". The atmosphere acts like the glass in a greenhouse, allowing much of the shortwave solar radiation to travel through unimpeded, but trapping a lo to fthelongwavehea tene rgyt ry ingtoescapebacktospace. This process makes the temperature rise in the atmosphere just as it does in the greenhouse. This is the Earth's natural greenhouse effect and keeps the Earth 33 ° C warmer than it would be without an atmosphere, at an average 15 ° C(59 ° F).
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Dr. Alan Doolittle, Ga Tech Understanding the Green House Effect Is the Green House Effect Real? YES! The Green House effect is unquestionably real. e average surface temperature of The average surface temperature of Earth is about 15 °C (59 °F) Without an atmosphere but at the same approximate distance from the sun, , the moon averages ~ 23 °C (9 °F) but during the lunar day, the rface temperature averages 107 surface temperature averages 107 C, and during the lunar night, it averages 153 °C Since the incoming light is at different frequencies than the outgoing light, some outgoing light can be referentially absorbed by various preferentially absorbed by various “Green House Gases”.
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Dr. Alan Doolittle, Ga Tech
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Lecture1ClimateChange - Dr.AlanDoolittle,GaTech

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