Remember to make a change you need to BE THE CHANGE ! Earth’s Atmosphere What will climate change look like years to come? Why is the ozone layer important? You can make a difference – You just have to Choose to. Remember to make a change you need to BE THE CHANGE !

Earth’s Atmosphere Atmosphere represents the gaseous outermost supersystem of our planet. The Earth's atmosphere is a blanket of gases approximately 350km (218 miles) thick. It is a large and complex system that interacts with the Sun, the land, and the oceans in order to produce both the Earths weather and climate.

Atmospheric Composition This supersystem consists of all the gases and particles in suspension as well as the gasses infiltrated in the ground.

Atmospheric Composition Main Constitutes and Their Roles: Nitrogen is used in the biosphere by plants and animals. Oxygen is life supporting and most of life on Earth is oxygen based. Inert Gases are found in constant proportions and their uses vary. Carbon dioxide is used by plants and is toxic to other organisms. Water Vapors vary widely and are the result of interactions with the hydrosphere

More on Composition Solid particles come either from the wind actions or from volcanic activities.

Structure of Earth’s Atmosphere Composition of the Atmosphere divided into three regions based on chemical make-up, temperature and function.

Atmospheric Structure Lets take a look at the chemical make-up. Heterosphere is the outer atmosphere. Features: It begins about 80 km (50 mi) altitude and extends to outer space. Gases not evenly mixed (hence, hetero) but distributed in layers according to weight. Makes up 0.001% of total atmospheric mass. Homosphere Extends from surface to heterosphere. Features: density  as altitude  blend of gases uniform except for concentration of ozone O3 from 19 to 50 km (12-31 mi) composition 78% N2, 21% O2, 0.93% Ar, 0.037% CO2 and trace gases.

Structure of Atmosphere: Temperature Atmospheric pressure (millibars) 200 400 600 800 1,000 120 110 100 90 80 70 60 50 40 30 20 10 (Sea Level) –80 –40 Pressure = 1,000 millibars at ground level Temperature (˚C) Altitude (kilometers) Altitude (miles) 75 65 55 45 35 25 15 5 Thermosphere Heating via ozone Mesosphere Stratosphere Ozone “layer” Heating from the earth Troposphere Temperature Exosphere Structure of Atmosphere: Temperature Temperature and pressure drop with height through the troposphere. The usual rate of decrease in temperature is known as the ELR (Environmental Lapse Rate) and averages 0.65 degrees Celsius per 100m.

Earth’s Atmosphere: Functions Ionosphere and Ozonosphere remove harmful wavelengths and charged particles. What happens when you fiddle with these? Ionosphere coincides with thermosphere and mesosphere. Absorbs cosmic rays, gamma rays, x-rays, some UV. And is also a Good reflector of radio waves Broadcasting stations use this fact to send programs thousands of miles away. They beam radio waves into the ionosphere at an angle, which are then reflected back to earth. Ozonosphere absorbs harmful UV and reradiates it as infrared. Skin cancer increases correlated with decreasing ozone - subject of CFC controversy.

Northern lights are caused by particles emitted from the Sun High energy particles from the Sun are trapped in the Earth’s magnetic field and directed down towards the Earth. The particles interact with atoms in the atmosphere producing light. The colors are from the spectral lines of atoms in the atmosphere.

Ionosphere As seen from space……………..and more!

Ozone in the StratosphereLayer Less ozone in the stratosphere allows for more harmful UV radiation to reach the earth’s surface. The ozone layer keeps about 95% of the sun’s harmful UV radiation from reaching the earth’s surface. Chlorofluorocarbon (CFCs) have lowered the average concentrations of ozone in the stratosphere. In 1988 CFCs were no longer manufactured.

OZONE DEPLETION IN THE STRATOSPHERE Ozone thinning: caused by CFCs and other ozone depleting chemicals (ODCs). Increased UV radiation reaching the earth’s surface from ozone depletion in the stratosphere is harmful to human health, crops, forests, animals, and materials such as plastic and paints.

• Immune system suppression Natural Capital Degradation Effects of Ozone Depletion Human Health • Worse sunburn • More eye cataracts • More skin cancers • Immune system suppression Food and Forests • Reduced yields for some crops • Reduced seafood supplies from reduced phytoplankton • Decreased forest productivity for UV-sensitive tree species Wildlife • Increased eye cataracts in some species • Decreased population of aquatic species sensitive to UV radiation • Reduced population of surface phytoplankton Figure 20.21 Natural capital degradation: expected effects of decreased levels of ozone in the stratosphere. QUESTION: Which five of these effects do you think are the most important? • Disrupted aquatic food webs from reduced phytoplankton Air Pollution and Materials • Increased acid deposition • Increased photochemical smog • Degradation of outdoor paints and plastics Global Warming • Accelerated warming because of decreased ocean uptake of CO2 from atmosphere by phytoplankton and CFCs acting as greenhouse gases

PROTECTING THE OZONE LAYER To reduce ozone depletion, we must stop producing all ozone-depleting chemicals. Figure 20-23