18A: What is the Atmosphere? How does the atmosphere change with elevation? Warm Up: Skydiving from Space! • Open your textbook to page 431 • Read the Case Study titled “Skydiving from Space” • Would you be interested in skydiving? Why or why not? What is the Earth’s atmosphere? Earth's Atmosphere - BrainPOP • Earth’s atmosphere is the envelope of gasses that surrounds the earth held by gravity • It is crucial to life on earth! • Earth’s atmosphere provides the gasses creatures need to live. • The atmosphere is evidence of God’s wonderful design! One Atmosphere, Two Ways to Study It Composition: the kinds of gasses it contains • Homosphere • Heterosphere Temperature: changes with elevation • Troposphere • Stratosphere • Mesosphere • Thermosphere • Exosphere Earth’s Atmosphere by Composition: Near the Ground • Nitrogen makes up more than ¾ of the atmosphere near Earth’s surface • Nitrogen’s main purpose is to dilute oxygen to the concentration that is best for life while avoiding a fire hazard! • The portions of these gasses are almost constant except for: • Water Vapor—varies from 0%-5% • CO2—varies from 0%-2% Earth’s Atmosphere by Composition: The Homosphere • Why is it called the homosphere? • The gasses that make up the air are thoroughly mixed together by winds & weather so they don’t separate, settle out, or form layers • Altitude of 80km • Beginning at 3km you would need pressurized O2 because there is too little pressure for air to supply all the oxygen you need! Earth’s Atmosphere by Composition: The Heterosphere • Why is it called the heterosphere? • Since there is little wind at these altitudes, gasses settle out by their atomic weight creating several layers of different gasses. • The heaviest gasses settle near the bottom and the lightest gasses are found at the top: • Molecular Nitrogen (N2) • Molecular Oxygen (O2) • Atomic Oxygen (O) • Helium (He) • Molecular Hydrogen (H2) The Atmosphere by Temperature • Use your textbook (pages 432 & 435) to fill in the charts in your notes. • Use your textbook to research each layer and include information for each layer in your diagram. • Be sure to include to include information for each temperature layer: • • • • Altitude Temperature Key Details Key Terms: Troposphere Lapse Rate Tropopause Stratosphere Jet Streams Stratopause Mesosphere Mesopause Thermosphere Thermopause Transitional Zone Exosphere Cycles & The Atmosphere • Key chemicals needed by living things are recycled in the natural environment making the amount of life on Earth possible! • There are 2 important cycles that involve the atmosphere: 1. The Carbon Cycle 2. The Nitrogen Cycle The Carbon Cycle • The carbon cycle is the flow of Carbon between living things, the earth, water, and the atmosphere. 1. There is Carbon in the atmosphere. 2. Plants get Carbon from the atmosphere during photosynthesis to build their tissues & produce fruits. 3. Animals & people eat the plants, taking in the Carbon and it becomes part of their tissues. 4. Carbon is exhaled back into the atmosphere. 5. When living things die and decay their carbon compounds enter the soil carbon reservoir. 6. Carbon can dissolve in surface water & groundwater entering lakes & oceans. The Nitrogen Cycle 1. The atmosphere is the largest Nitrogen reservoir for the Nitrogen cycle. 2. Air has lots of Nitrogen (N2), but most living things cannot use it in the form it is in. 3. Atmospheric Nitrogen (N2), must be converted into Organic or Fixed Nitrogen compounds such as ammonia (NH3 ) 4. Nitrogen Fixing Bacteria live in the soil, in some plants, and aquatic/marine environments. They convert N2 into ammonia NH3 or ammonia compounds. 5. Lighting is a natural way atmospheric nitrogen is converted into fixed nitrogen. One Atmosphere, Two Views The Old Earth Story 1. Within several hundred million yrs. of earth’s birth, a moon forming collision occurred melting the entire earth. 2. As the earth cooled, there was no oxygen. 4. Volcanoes and ice comets changed the atmosphere to include water. 5. Sometime during the first billion yrs. life appeared from nonlife—anerobic bacteria 6. Ultraviolet light from the sun broke down H2O vapor into O & H allowing oxygen producing cyanobacteria to evolve from the anerobic bacteria 7. Oxygen Catastrophe: 2.4 billion years ago extra oxygen from surface rocks collected in the atmosphere causing the O2 levels to become so high that it killed off most of the anaerobic organisms paving the way for more advanced forms of life to evolve 8. Photosynthetic forms of life evolved producing the oxygen rich atmosphere we have today. The Young Earth Story • We don’t know when God created the atmosphere because it is not specifically mentioned in the Creation story in the Bible. • Genesis 1:6-8 We can assume that when God formed the firmament between the waters above and the waters below on Day 2 He also created the atmosphere in preparation for the creation of plants on Day 3. • The Flood changed the atmosphere: • Volcanic activity • Changes in the size & shape of Earth’s oceans • Climate & weather changes Air Care: How & Why to Care for the Atmosphere • Air pollution forms when gasses or particles that enter the air interfere with breathing or are hazardous in other ways. • Smog is the kind of air pollution that makes many cities appear hazy • Air pollution kills about 5.5 million people a year • Can be indoor or outdoor • Air pollution can come from: • Natural Sources: volanoes, forest fires, radioactive radon, molds, pollen • Human Sources: automobiles, fossil fuel powerplants (GREENHOUSE GAS EMISSIONS) • Emissions are … • How can we exercise good & wise dominion?
