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Global Warming

Global Warming. Climate and Weather. Atmosphere and Weather. Earth is surrounded by a layer called the atmosphere. It consists of a mix of gases, water vapour, dust and chemicals. The atmosphere provides the oxygen and carbon dioxide that all living things must have.

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Global Warming

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  1. Global Warming Climate and Weather

  2. Atmosphere and Weather • Earth is surrounded by a layer called the atmosphere. It consists of a mix of gases, water vapour, dust and chemicals. • The atmosphere provides the oxygen and carbon dioxide that all living things must have. • Changes in the atmosphere provide the weather and affects the way you live. • Weather is a day-to-day change in the atmosphere but a longer trend in atmospheric behaviour is called a climate. • Climate varies with geographic location: lots of rain and snow, dry, hot and cold.

  3. Atmosphere and Weather • Air is a mix of nitrogen (78%), oxygen (21%) and other gases (argon, carbon dioxide, etc.). • There is also some water vapour but this varies with atmospheric conditions. • In a given amount of air, up to 4% may be water vapour. • The air usually contains dust, ash and chemicals. • The dust could be soil or pollen and salt spray from the oceans. • The ash arrives from forest fires and volcanic activity.

  4. Atmosphere and Weather • Pollution adds unnatural chemicals into the air, which mix with air making weak acids. • When pollutants get trapped near the Earth, a mix of smoke and fog (SMOG) results. • Gravity pulls each air molecule down to create air pressure. It is the highest at sea level. • Air pressure varies with altitude and air temperature. • Meteorologists use air pressure to predict storm movements. • Changes in air pressure make the winds.

  5. Atmosphere and Weather • Temperature is the amount of heat energy in the air. (Affects air pressure and water vapour content.) • Humidity is the amount of water vapour in the air. (Affects clouds and rain.) • These three factors (air pressure, temperature and humidity) are used to forecast the weather.

  6. Wind • The air is heated more at the equator than at the poles. • This heated air moves upwards to the poles and the cooler air moves down to the equator. • The Earth’s rotation churns the air into wind belts, stretching around the Earth. (Coriolis effect) • Wind blows primarily in one direction in a wind belt. • A region between two belts has wind that shifts rapidly (between directions) or it won’t blow at all. • Wind is the movement of air from high to low pressures.

  7. Jet Streams • Jet Streams blow above the wind belts at the upper edge of the troposphere. • These are narrow bands of high speed winds. (Often faster than 300 km/h). • There are several jet streams around the Earth at various latitudes. (2 or 3 in the North or South hemispheres) • During cooler months, jet streams are closer to the equator and move faster. • Jet stream changes cause squalls, storms and cyclones.

  8. Jet Streams

  9. Storms • Storms on the Earth’s surface are controlled by the jet stream paths. •  Storms are simply the way that nature moves energy in the atmosphere. • There are 3 categories of Violent Storms: Hurricanes, Tornados and Thunderstorms.

  10. Hurricanes • Hurricanes form over warm waters of the South Atlantic between two wind belts. • The calm centre is called the eye of the hurricane. • They may reach sizes of 640 km across and have winds up to 320 km/h. • The US is hit about twice a year. • They can also create tornadoes and violent thunderstorms.

  11. Ocean Currents • Ocean currents also move thermal energy around the Earth and are affected by the Coriolis effect.

  12. Isabel

  13. Tornados • Tornadoes are small but violent twisting storms. • These form ahead of strong cold fronts, travel on land at about 30-60 km/h but winds in the funnel may reach 470 km/h. • The centre of a tornado is at a very low pressure. • When objects like houses at normal air pressure interact with the core, they explode into it.

  14. Thunderstorms • Thunderstorms produce high winds, rain, hail and lightning. • Lightning strikes take place thousands of times every day. • These form when warm, moist air is thrust rapidly into the atmosphere. • The cumulus clouds become cumulonimbus and may reach heights of 27 km. • The rapidly moving winds generate friction, creating lightning. • If there is a strong updraft in a cloud, hail can result. • Thunderstorms are very common and several hundred of them are occurring right now. • The average thunderstorm releases the same amount of energy as an atomic bomb.

  15. Weather Forecasting • Meteorologists study the atmosphere and how it works to predict its behaviour. • Weather stations, barometers, satellite images and weather balloons all help in thisstudy. • Air masses, low and high-pressure areas, fronts and violent weather are all shown on maps. • A forecast is a prediction on what might happen. • It includes information on the condition of the atmosphere, a description of how it has behaved and a prediction on how it will behave. • Forecasts pay close attention to violent weather for pilots and farmers.

  16. Earth’s Biosphere • The biosphere is the thin layer of Earth that has conditions to support life. • The atmosphere is the gas layer around the planet. • The lithosphere is the rock layer around the planet. • The hydrosphere is the water layer around the planet.

  17. Atmosphere Layers • The bottom layer of the atmosphere is called the troposphere and is 0-10 km high and is 20 to -600C. This is where all weather occurs. Contains most of the CO2, water, (80% of whole atmospheric gas) and dust. Can support life. • The second layer is called the stratosphere, is 40 km thick (10-50 km high) and is 0 to -600C. Very thin clouds exist here. Contains most of the ozone.

  18. Atmosphere Layers • The 3rd layer is the mesosphere, is 50-80 km high and is 0 to-1000C. It has very little gas, low pressure and few O2 molecules. • The final layer is called the thermosphere at greater than 80 km high and ranges from -100 to 1000oC. Very little gas is here but gets very hot in the day and very cold at night.

  19. Biomes • A biome is a large geographical region with defined ranges of precipitation and temperature. • There are 6 biomes in Canada: Tundra, Boreal forest (taiga), Temperate deciduous forest, Temperate grassland, Temperate Coniferous forests and Mountains. • Mountains can show different types of biomes as you climb, with tundra at the top of the higher mountains. • There is no distinct line between biomes, and some biomes may overlap characteristics.

  20. Solar Energy and Weather • There are three methods of heat transfer: conduction, convection and radiation. Conduction: • The transfer of heat by contact when high-speed molecules hit slow speed molecules, making them move faster. • Heat always flows from hot to cold. (Molecules vibrate in solids and do not move)

  21. Solar Energy and Weather Convection: • When high-energy molecules move due to changes in density. • Hot air will rise as it is less dense than cold air. • Cooler air will move into its place creating a convection current. • Holding your hand above a candle is heating by convection. • This occurs in liquids as well. • Some stoves use convection heating and heat things quickly.

  22. Solar Energy and Weather Convection: • Convection also explains the wind patterns at the beach. • During the day, the beach is hotter so it has more hot air rising. • The cooler air above the water rushes in to take its place creating an onshore breeze. • At night, the heat stored by the high heat capacity of water, rises up and the cooler air on the beach moves out to create an offshore breeze. • Wind, in general is a result of convection and the Earth’s rotation.

  23. Solar Energy and Weather Radiation: • This is the emitted heat from hot objects. • Radiation is an electromagnetic wave. • Heat travels as an infrared wave. • These waves can travel through space. • The radiant energy from the sun is important for life and drives all weather systems

  24. Solar Energy and Weather Radiation: • Solar radiation on the Earth’s surface is about 50% of that emitted by the sun. (The amount at our atmosphere is 1367 J/m2s: the solar constant). • The rest is lost as follows: 20% is absorbed by the many kilometres of atmosphere (air and clouds) and the remaining 30% is reflected off clouds, air and the ground itself. • The Earth radiates energy into space as well such that the Earth does not cook from the constant solar energy. (lost as heat)

  25. Solar Energy and Weather Radiation: • The oceans maintain a fairly consistent temperature because water has a special property called the specific heat capacity. • It takes a lot of energy to heat water, which makes it good for car radiators. • The energy goes into making the water molecules move faster.

  26. Greenhouse Effect • Insolation is the amount of solar radiation received by a region of the Earth’s surface. • The absorption of thermal energy by the atmosphere is called the natural greenhouse effect. • Water vapour, carbon dioxide, nitrous oxide and methane are called greenhouse gases. • Water is the main contributor of the natural greenhouse effect. • The net radiation budget is the difference between the amount of incoming radiation and the amount of outgoing radiation. • Albedo measures the percent of incoming radiation the surface reflects. (Bright snow reflects a lot).

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