Love is like oxygen, You get too much you get too high, Not enough and you're going to die, Love makes you high. Sweet, Love is Like Oxygen

Assignment: Check out the Environmental Protection Agency's Global Warming website. Please read the two subsections under each of the "Climate," "Emissions," and "Impacts" sections. You might also want to peruse the "News" section for recent developments in the study of climate change. Also, calculate how many pounds of carbon you release into the air from your normal activities using the EPA's Personal Greenhouse Gas Calculator Sign up for a time slot for Observing Lab #2. Problem Set #5 is due Thursday at 1:00 pm.

In Class: Question to Ponder Saturn has a mass of 5.68 x 1026 kg, and a volume of 9.17 x 1023 m3. If you could build a big enough bathtub and fill it with water, would Saturn float in it or sink? a) float b) sink How to Make an Atmosphere Earth's atmosphere has been around for a large fraction of the Earth's history. Possibly made from subductive vulcanism. Subducting some of the crust effectively "cooks" it, liberating gases as the crustal material is broken down into simpler compounds. Possibly made from comet bombardment. Comets are mainly ices (of water, carbon dioxide, methane and ammonia), and they were probably quite plentiful in the early history of our solar system. Either way (or perhaps through a combination of both processes), the early Earth atmosphere was filled with carbon dioxide (CO2), water (H2O), ammonia (NH3),and methane (CH4). This noxious mix would be poisonous to any life we understand, so it must've been "cleaned up" since then. How to make the Atmosphere Breathable Solar irradiance breaks up NH3 and CH4, and then H floats away because Earth's gravity is too weak to keep it around. The presence of liquid water allows for a lot of the CO2 to be absorbed. Life, particularly plant life and mollusks, absorb CO2 and store the carbon as shells or stalks, limbs, etc. Life processes transform the atmosphere and fill it with oxygen so that more complex animal life can arise. Atmosphere as Protector I: Ozone Normal oxygen is O2. Ozone is O3. Produced when sunlight dissociates normal oxygen, producing free single atoms. These bind with other O2 to produce ozone very high in our atmosphere. Ozone absorbs ultraviolet sunlight, preventing it from reaching the Earth's surface. "Nature's sunscreen" Ozone Depletion Ozone is destroyed by chlorine (Cl) and Bromine (Br) when these substances are released into the atmosphere. Chloro-Fluoro-carbons (CFC's) used in refrigeration equipment have large amounts of Cl. Cl and Br react with ozone, destroying it. Widespread use of this material and other related compounds has substantially increased Cl and Br concentrations in our atmosphere, and ozone levels have dropped. The Ozone Hole Near the poles, ozone levels have dropped substantially. Each September a large "ozone hole" appears over Antarctica. Ozone depletion is largest near the poles because the destruction reaction with Cl and Br occurs most at low temperatures. Solving the Problem All scientists agree that ozone depletion and the ozone hole are a direct result of human activity. No large natural sources of Cl and Br. in 1987, many nations signed the Montreal Protocol to reduce and eventually eradicate the use of CFC's and other ozone-harming compounds. Since then, production and emission of these substances has been reduced, especially in industrialized countries. We've found alternatives that work almost as well and don't cost a whole lot more. It's likely that we caught the problem in time and solved it before irreversible damage occurred. Scientists now estimate that the ozone hole will slowly decrease in size, and the ozone layer will return to historically normal levels in 50 years or so.