Intro. to the Greenhouse Effect

Climate and Climate Change

Intro. to Greenhouse Effect:Outline

• Atmospheric Gases: “Greenhouse” or Not?– How gases can store heat energy

• Step-by-Step of the Greenhouse Effect– How energy enters Earth’s systems– How energy is absorbed and retained

• Impact on Earth’s Climate– Prehistoric data– Modern data

Atmospheric Gases:Non-“Greenhouse”

These gases are simple, either one atom or two.

They store energy through translating or (sometimes) rotating.

Atmospheric Gases:“Greenhouse”

These gases are complex, at least three atoms bonded together.

They store energy through translating, rotating, or complex vibrations.

For extreme physics details, CLICK HERE

Greenhouse Effect Steps:Overview

Greenhouse Effect Steps:1. Sun’s Energy Enters

• Most of the atmosphere is transparent to “visible” light– Why you can see

through it most of the time

• Most incoming solar radiation is “visible” kind (see graph later) By Handyhuy (Own work) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via

Wikimedia Commons

Greenhouse Effect Steps:2. Ground Absorbs Energy

• You can’t see through the Earth’s surface – Ground and other

surface features absorb visible light and heat up

• E.g., dark objects absorb more light and heat up more easily

http://blogs.kxan.com/2011/06/17/will-it-be-hottest-summer-ever/

Greenhouse Effect Steps:3. Ground Radiates IR Energy

• Infrared radiation (IR) is released from warm bodies– E.g., the hot ground

releases it in all directions

• “Night vision” goggles pick up IR, by the way

By Brocken Inaglory (Own work) [Public domain], via Wikimedia Commons

Greenhouse Effect Steps:4. GHGs Absorb IR Energy

• Greenhouse gases (GHGs) have the complex motions that match the IR energy– IR traveling from the

surface hits gases– GHGs begin vibrating

(i.e., heating up, storing the energy)

• Heated GHGs also release IR!

By Nick84 [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons

Greenhouse Effect Steps:Revisited

Impact on Earth’s Climate:Prehistoric Data

By Vostok-ice-core-petit.png: NOAA derivative work: Autopilot (Vostok-ice-core-petit.png) [CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or GFDL (http://www.gnu.org/copyleft/fdl.html)], via Wikimedia Commons

Impact on Earth’s Climate:Modern Data (Slide 1)

By US Govt (NOAA (http://www.esrl.noaa.gov/gmd/aggi/)) [Public domain], via Wikimedia Commons

Impact on Earth’s Climate:Modern Data (Slide 2)

• “Global mean land-ocean temperature change from 1880–2013, relative to the 1951–1980 mean. The black line is the annual mean and the red line is the 5-year running mean. The green bars show uncertainty estimates.”

By NASA Goddard Institute for Space Studies (http://data.giss.nasa.gov/gistemp/graphs/) [Public domain], via Wikimedia Commons

Wikipedia contributors. "Global warming." Wikipedia, The Free Encyclopedia. Wikipedia, The Free Encyclopedia, 12 Oct. 2014. Web. 14 Oct. 2014.

Check yourself

• Is heat trapped on the way in or the way out?• Given what you know about Mars and/or

Venus, how do you think the greenhouse effect impacts their climates?

• How “effective” a greenhouse gas do you think the following molecule is?

By Walkerma (Own work) [CC0], via Wikimedia Commons