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THE ATMOSPHERE

THE ATMOSPHERE. Weather & Atmosphere What does the weather forecast say? 36°F | 2°C Condition: Clear Humidity: 65% Wind: N at 2 mph. 1. THE AIR AROUND YOU. Weather is the condition of Earth’s atmosphere at a particular time and place.

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THE ATMOSPHERE

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  1. THE ATMOSPHERE

  2. Weather & Atmosphere • What does the weather forecast say? • 36°F | 2°C • Condition: Clear • Humidity: 65% • Wind: N at 2 mph

  3. 1. THE AIR AROUND YOU • Weather is the condition of Earth’s atmosphere at a particular time and place. • Earth’s atmosphere is the envelope of gases that surrounds the planet.

  4. Composition of the Atmosphere 1.Nitrogen: (N2) • ¾ of the air we breath (Most abundant gas) • Nitrogen molecule has 2 atoms of Nitrogen 2.Oxygen: • Less than ¼ of the volume. It is involved in other processes • Oxygen molecules (O2) has 2 atoms of oxygen. • Ozone (O3) is a form of oxygen that has 3 atoms of Oxygen

  5. Antoine-Laurent Lavoisier has been called the founder of modern chemistry， 1743.8.26-1794.5.8. French Among his important contributions were the application of the balance and the principle of conservation of mass to chemistry, the explanation of combustion and respiration in terms of combination with oxygen.

  6. 3.Carbon Dioxide: • Each molecule of CO2 has 2 atoms of oxygen and 1 of carbon. • It is essential to life (plants). 4.Other gases: • Argon (Ar) etc. • Remain gases are called trace gases, because only small amounts of them are present. 5.Water vapor: • Air is not dry because it contains water vapor • Important role in the Earth’s weather.

  7. 6.Particles: • Pure air only exists in laboratories. • In the real world air contains: dust, smoke, salt, chemicals… • Importance of the atmosphere • Earth’s atmosphere makes conditions on Earth suitable for living things. (Water, Energy, Mild temperatures, radiation and meteorites protection)

  8. 2. AIR PRESSURE • The weight of the atmosphere itself is constantly pressing on your body (I.e.: backpack) • Properties of air • Air has mass • Density density= mass/volume • (More molecules, greater density)

  9. Pressure • The force pushing on an area or surface • Air pressure is the result of the weight of a column of air pushing down on an area. • Denser substance has more mass per unit volume than a less dense one, so denser air exerts more pressure than less dense air

  10. Measuring Air Pressure • Barometer is an instrument that is used to measure air pressure. There are 2 types: • Mercury barometer (At sea level the mercury column is about 760mm high on average) • Aneroid Barometer  (Aneroid means without liquid)

  11. Units of Air Pressure • milibar (mbar or mb) • Atmosphere (atm) • 1atm= 1060 mbar • 1atm= 760 mmHg or Torricelli (tor) • Altitude is the distance above sea level. • Air pressure decreases as altitude increases • As air pressure decreases, so does density (I.e.: air at the top of a mountain).

  12. 3. LAYERS OF THE ATMOSPHERE • Scientist divide Earth’s atmosphere into four main layers classified according to changes in temperature. These layers are: • The troposphere • The stratosphere • The mesosphere • The Thermosphere • The Ionosphere • The Exosphere

  13. The Troposphere • Earth’s weather occurs here. • Tropo- means “turning” • The depth varies in the equator(9 Km) and in the poles(15Km). • It contains almost all of the mass of the atmosphere • As altitude increases in it, the temperature decreases.

  14. The Stratosphere • It extends from the top of the troposphere to about 50 km above earth’s surface. • It contains the ozone layer (O3). • Lower stratosphere colder than the upper. • The ozone protects Earth’s living things from dangerous ultraviolet radiation from the Sun.

  15. The Mesosphere • A drop in the temperature marks the beginning of the next layer. • Meso means “middle” • It is the layer of the atmosphere that protects Earth’s surface from being hit by most meteoroids. • Meteoroids are chunks of stone and metal from space.

  16. The Thermosphere • Near the top of the atmosphere, the air is very thin. • It has no outer limit • Thermo means “heat”. Air in here is very hot, because sunlight strikes it first. • The Thermosphere is divided into two layers: • The lower layer is called the Ionosphere: • The outer layer is called the Exosphere: • Temperature is the average amount of energy of motion of each molecule of a substance

  17. The Thermosphere is divided into two layers: • The lower layer is called the Ionosphere: • It begins about 80 km above the surface and extends to about 400 km. • Energy from the Sun causes gas molecules in the ionosphere to become electrically charged particles called ions. • Radio waves bounce off ions in the ionosphere back to Earth’s surface. • Northern lights or Aurora Borealis occur here. They are caused by particles from the Sun that enter the ionosphere near the poles. These particles strike atoms in the ionosphere, causing them to glow. • The outer layer is called the exosphere: • It is the outer portion of the thermosphere. • It extends from about 400 km outward for thousands of km.

  18. 4. AIR QUALITY • Not everything in the air is healthy(tiny particles or small amount of harmful gases) • Pollutants are harmful substances in the air, water or soil.

  19. Sources of Pollution • Natural sources: forest fires, soil erosion and dust storms release a great deal of smoke and dust into the air. • Human activities: such as farming and construction, can send soil and dust into the air. Most air pollution is the result of burning fossil fuels (half from motor vehicles, the other from factories, power plants…). • Burning fossil fuels produces a variety of pollutants, including carbon monoxide, nitrogen oxides and sulfur oxides.

  20. Smog and Acid Rain • Caused by the burning of fossil fuels • London-type Smog • 100 years ago “dirty” air in London (coal burning) • Air was full of soot • Smog= smoke and fog (describe this air pollution) • Photochemical Smog • The brown haze that develops in sunny cities is called photochemical smog. It is formed by the action of sunlight on pollutants such Hydrocarbons and nitrogen oxides (Brownish mixture of ozone and other pollutants) • Ozone in the stratosphere is good, but it in the troposphere is a pollutant.

  21. LONDON TYPE SMOG

  22. PHOTOCHEMICAL SMOG

  23. Acid Rain • When rain contains more acid than normal. • It forms when nitrogen oxides and sulfur oxides combine with water in the air to form nitric and sulfuric acid. • Sometimes strong enough to damage the surfaces of building and statues, but also affects water.

  24. AIR QUALITY • AIR QUALITY INDEX (AQI) • The AQI is an index for reporting daily air quality. • It tells you how clean or polluted your air is, and what associated health effects might be a concern for you. • The AQI focuses on health effects you may experience within a few hours or days after breathing polluted air

  25. Where to check Beijing AQI: • http://iphone.bjair.info/(From US Beijing embassy) • Improving Air Quality • Law and regulation to reduce air pollution (in some countries such as US) • Voluntary measures: • Car pooling • Public transport • Better design of factories (recycling systems…)

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