Earth's Resources: Introduction to Air and Atmosphere

1. Earth's Resources: Introduction to Air and Atmosphere The atmosphere is a blanket of gases that extends from the surface of the Earth and reaches over 560 kilometers (348 miles)

2. Structure of Earth's Atmosphere The Troposphere The troposphere is the lowest region of the Earth's atmosphere, where masses of air are very well mixed together and the temperature generallydecreases with altitude. Occasionally, a temperature inversion occurs, and the temperatures actually increase with altitude within this zone. Most weather on Earth occurs within the troposphere, because this is where the water vapor is. General Altitude of the troposphere is from 14-18 km.

3. Environmental Lapse Rate The environmental lapse rate is the actual decrease in temperature with an increase in altitude through the troposphere. Sometimes, ELR is also known as “normal lapse rate. While many things influence the “normallapse rate of temperature, in general, the temperature decreases with altitude at an average rate of .65oC /100 meters. Take a moment to discuss with your partner what types of factors may impact the normal lapse rate within the troposphere.

4. The Stratosphere In the stratosphere, the air is stable and less turbulent. • The temperature of the air within the stratosphere increases with altitude. This increase in temperature with altitude is due to the presence of stratospheric OZONE near an altitude of 25 km. Ozone molecules absorb high-energy ultraviolet rays from the sun, which warm the atmosphere at that level. The stratosphere extends to 50 km.

5. Limb The Mesosphere In the Earth's mesosphere, the air masses are relatively mixed together and the temperature decreases with altitude. This is also the layer in which a lot of meteors burn up while entering the Earth's atmosphere. The mesosphere extends from the top of the stratosphere (50 km) to an altitude of about 90 kilometers, and can be detected by looking at the limb.

6. The Thermosphere When the Sun is active, temperatures within this zone can reach up to 1,500°C, or higher! The thermosphere can extend above the Earth’s surface as far as 480 km. The thermosphere also includes the region of the Earth's atmosphere called theionosphere. When a rapidly moving particle, such as an electron, collides with a gas atom, an electron is ejected from the atom, leaving a positively charged ion. • Ionization processes release energy, which heats up the upper atmosphere. Temperature, therefore, increases with altitude in the ionosphere and it is extremely hot compared to surface temperatures.

7. More about the Ionosphere Even thought the ionosphere represents less than 0.1% of the total mass of the Earth's atmosphere, it is extremely important. • Different regions of the ionosphere makelong distance radio communicationpossible by reflecting the radio waves back to Earth. • The space shuttle flies in this area of the atmosphere, and this is also where the aurora borealis, and aurora australis are found. • Aurorasare wispy curtains of light caused when the sun strikes gases in the atmosphere above the Polar regions.

8. The Exosphere, and beyond The region of our atmosphere where atoms and molecules escape Earth’s gravitation and move into space is referred to as the exosphere. This is truly the upper limits of Earth’s atmosphere, and some of our satellites are stationed in this area. • It is 500 to 1000 km above the Earth’s surface A region within and beyond the exosphere is known as the magnetosphere. It is not truly a layer of Earth’s atmosphere so it is not bound by gravitation, but by magnetism.

9. The Greenhouse Effect

10. When learning about the Greenhouse Effect, it is important to understand the electromagnetic spectrum, and the lengths of waves within it. • Radio waves • Microwaves • Infrared waves (IR) • Visible light (ROYGBIV) • Ultra Violet (UV) • X-Rays • Gamma Rays In order, from longest to shortest wavelengths, the spectrum is as follows:

11. Sunlight travels through space in a very short and powerful wavelength, known as Ultra violet (UV). • Some UV radiation is reflected or absorbed by the ozone (O3) molecules located in our stratosphere This UV light is not seen by our eyes (as only visible light is within the spectrum our eyes can detect). However, it can be detected by our skin when we get a sunburn, or feel warmed by the sun.

12. Some UV radiation as well as visible light is able to penetrate the atmosphere and hit the Earth’s surface. • Some of that UV radiation and visible light which reaches the surface is absorbed by vegetation, soil, water, and rock. As you may remember, it is this heating of the water over our tropical oceans that drives much of the climate on our planet. Which Earth surfaces do you think are responsible for the greatest absorption?

13. Albedo Albedo is the reflection coefficient, or the reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it. Albedo is measured on a scale from zero for no reflecting power of a perfectly black surface, to 1 for perfect reflection of a white surface. Typical albedo ranges from 0.9 for fresh snow, to about 0.04 for charcoal, black asphalt, and lava rock

14. Some of that radiation (which is absorbed) is converted, and re-radiated back into Earth’s troposphere as long wave, less powerful radiation known as Infra-red • This long wave Infrared radiation (IR) is unable to penetrate the Earth’s greenhouse gas layer, and becomes trapped, as heat energy near the surface in our atmosphere The IR radiation (just like the UV) is not seen by our eyes, but it can be felt as warmth on our skin. Many scientists believe it is this effect that is causing the global rise in temperatures known as Global Warming.

15. Global Warming was first recognized by Svante August Arrhenius in 1896. His meteorological studies made him conclude that the weather patterns had changed in Sweden since the beginning of the industrial revolution (1800). He proposed that burning of fuels was causing these changes. He was correct of course in that burning fossil fuels indeed had contributed to global warming. • 80% of the Earth's increase in temperature is due to the burning of fossil fuels like coal and oil and the resulting CO2 emissions. The industrial revolution has been fueled by coal and oil. • The other 20% occurs naturally and comes from decomposing vegetation.

16. The Chief Culprits: Greenhouse Gases • CO2 (carbon dioxide): 25% increase in last 200 years. • CFCs (chlorofluorocarbons): used as solvents to clean computer chips and keep the cool (a.k.a. Freon) in air conditioners. One CFC molecule can absorb 20,000 times more infrared energy than CO2 molecules. • CH4 (methane): increasing 11% per year. One CH4 molecule can absorb 25x the IR as CO2 molecules (caused by burning of biomass, and livestock emissions) • NOx (nitrous oxides): accelerated by the use of nitrogen-based fertilizers. Absorbs 250x more IR than CO2 • O3 (ozone): very minor influence • H2O (water vapor): not caused by humans Current estimates indicate that CO2 is responsible for about one half the problem. CH4 and NOx each contribute one fourth.

17. As ominous as this all sounds, this greenhouse effect is vital to life on Earth. With no atmosphere on the moon: (no atmosphere means no greenhouse effect) • In the illuminated half, the temperatures often reach 216° F • In the dark half, the temperatures often plummet to -243° F Without greenhouse effect on Earth, the average temperature would be -27° F The one greenhouse gas that has truly been increasing in the past 50 years is carbon dioxide. Loss of rainforests that take in carbon dioxide, and the burning of fossil fuels by cars, factories and plants which release carbon dioxide are part of the causes.

18. Ozone In the stratosphere, (6 to 30 miles above the surface) the chemical compound ozone plays a vital role in absorbing harmful ultraviolet radiation from the sun. • In the Troposphere: • low concentrations • sources: • hydrocarbons • small amounts of stratospheric ozone O3

19. Natural Tropospheric Ozone: • Lightning and • static discharges Ozone gives off the acrid smell after a lightning discharge. Some ozone is also produced when natural hydrocarbons, such as the terpenes in coniferous trees react with nitrogen oxides in the atmosphere and sunlight.

20. The ozone that is a byproduct of certain human activities does become a problem in the troposphere, and this is what we think of as 'bad' ozone. With increasing populations, more automobiles, and more industry, there's more ozone in the lower atmosphere. • Since 1900 the amount of ozone near the Earth's surface has more than doubled. • Unlike most other air pollutants, ozone is not directly emitted from any one source. • Anthropogenic tropospheric ozone is formed by the interaction of sunlight, (particularly ultraviolet light) with hydrocarbons and nitrogen oxides (NOx), which are emitted by automobiles, gasoline vapors, fossil fuel power plants, refineries, and certain other industries.

21. In urban areas in the Northern Hemisphere, high ozone levels usually occur during the warm, sunny summer months (from May through September). • Typically, ozone levels reach their peak in mid to late afternoon, after the sun has had time to react fully with the exhaust fumes from the morning rush hours. • In early evening, the sunlight's intensity decreases and the photochemical production process that forms ground level ozone begins to subside.

22. While stratospheric ozone protects us from ultraviolet radiation, in the troposphere this irritating molecule damages forests and crops; destroys nylon, rubber, and other materials; and injures or destroys living tissue. It is a particular threat to people who exercise outdoors or who already have respiratory problems. • Ozone affects plants in several ways. High concentrations of ozone cause plants to close their stomata. • Closed Stomata means: • Slowed photosynthesis • Little or no food produced • Eventually starving plant Sometimes ozone may enter open stomata, and directly do damage to internal cells

23. When ozone pollution reaches high levels, pollution alerts are issued urging people with respiratory problems to take extra precautions or to remain indoors. Ozone has been linked to tissue decay, and the promotion of scar tissue formation. It can impair an athlete's performance, create more frequent attacks for individuals with asthma, cause eye irritation, chest pain, coughing, nausea, headaches and chest congestion and discomfort. It can worsen heart disease, bronchitis, and emphysema.

24. The most dramatic phenomenon associated with the stratospheric ozone layer over recent decades has been the rapid growth in the region of an ozone “hole” in the Antarctic during the spring The depletion of ozone can greatly be seen over Antarctica in the Southern Hemisphere where the region has total ozone levels at less than 220 Dobson Units (DU) Oct 1-15 2009 The ozone hole has gotten smaller each consecutive year, since 2006. While the use of ozone depleting chemicals, such as CFCs, was phased out in 1987 under the Montreal Protocol, they are still present in the atmosphere, and only decreasing at a rate of 1% per year.

25. Possible Solutions Just transport the ozone ! Ozone molecules don't last very long, with or without human intervention. The vehicle necessary to transport such enormous amounts of ozone into the stratosphere does not exist now, and, if it did, it would require so much fuel that the resulting pollution might undo any positive effect. • Decrease production of chemicals that break-down ozone • Find alternatives to those chemicals

26. Christian Friedrich Schoenbein discovered ozone in 1839. He used the reactivity of ozone to measure its presence and demonstrate that it is a naturally occurring component of the atmosphere. He developed a way to measure ozone in the troposphere using a mixture of starch, potassium iodide, and water spread on filter paper. The paper, called Schoenbein paper, changes color when ozone is present. Ozone causes iodide to oxidize into iodine. KI + O3 + H2O--> KOH + O2 + I2 I2 + starch --> blue color 2 2 This test is based on the oxidation of ozone. Ozone in the air will oxidize the potassium iodide on the test paper to produce iodine. The iodine reacts with starch, staining the paper a shade of purple. The intensity of the purple color depends on the amount of ozone present in the air. The darker the color, the more ozone is present. Will the results be Qualitative or Quantitative ? Tomorrow, we’ll make some Schoenbein Paper!