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Biophysical Interactions Atmosphere Hydrosphere Lithosphere Biosphere Case study – Murray Darling Basin The four spheres • Define the following: -Atmosphere -Hydrosphere -Lithosphere -Biosphere The Atmosphere • The transparent, odourless mass of air surrounding the Earth. • It is made up of the -troposphere -stratosphere -mesosphere -thermosphere Troposphere • The Troposphere is the lowest layer of the atmosphere and measures about 12 km. • It contains over 75 percent of all the atmosphere's gases and vast quantities of water and dust. As the sun heats the ground, it keeps this thick mixture churning. • The weather is caused by these churnings of the mass. • The troposphere is normally warmest at ground level and cools higher up where it reaches its upper boundary. Stratosphere • The Stratosphere extends from the tropopause up to its boundary (the Stratopause),50 km above the Earth's surface. • In this layer there is 19 percent of the atmosphere's gases and it contains little water vapour. • Compared to the troposphere it is calm in this layer. The movements of the gases are slow. Within the stratosphere is the ozone layer, a band of ozone gas, that absorbs harmful ultraviolet rays of the sun. Mesosphere • The mesosphere is the next layer above the stratopause and extends to its upper boundary (the Mesopause), at 80 km above the ground. • The gases in the mesosphere are too thin to absorb much of the sun's heat. • Although the air is still thick enough to slow down meteorites hurtling into the atmosphere. They burn up, leaving fiery trails in the night sky. • The temperatures in the mesosphere drop to -120 ºC) at the mesopause. Thermosphere • The Thermosphere is the layer above the mesopause. The gases of the thermosphere are even thinner than those in the mesosphere, but they absorb ultraviolet light from the sun. • Because of this, the temperatures rise to 2,000 ºC at the top. • This is at a height of 700 km of the earth's surface. Composition • What is the composition of the Earth’s atmosphere? Composition Pressure systems • List the characteristics of low pressure systems: Low pressure systems • Ascending air • Strong winds • Chance of rain • Clockwise (Sth Hemi) • Anticlockwise (Nth Hemi) • Most intense events are cyclones and tornadoes High pressure systems • List the characteristics of high pressure systems High pressure systems • Fine weather • Calm conditions • Descending air • Clockwise (Nth Hemi) • Anticlockwise (Sth Hemi) Air mass • A body of air that has been affected by a large area of the Earth’s surface, such as an ocean or continent, is known as an air mass. • A front is where two air masses meet Fronts • What is the difference between a warm and cold front? Warm fronts • Warm air mass on the move • Clashes with and rises above the cold air mass • Results in rainfall • Labeled with bumps Cold fronts • Cold air mass on the move • Clashes with and pushes up the warm air mass • Results in rainfall and falling temperatures • Labeled with spikes Synoptic charts • What can we read from a synoptic chart? Synoptic charts • Wind direction • Wind speed • Air pressure (hPa) • Air masses • Cold / warm fronts • Rainfall • Air temperatures Summer conditions • Highs in southern Australia – drier • Lows in Northern Australia – wet monsoon season Winter conditions • Draw what would be expected for typical winter conditions. World pattern of climate • What factors determine the world pattern of climate? Climatic factors • 1. Solar radiation • 2. Revolution of the Earth around the sun • 3. Composition of the atmosphere • 4. Distribution of continents and oceans • 5. Topography Insolation variations • Equatorial areas receive more direct solar radiation than polar areas. Earth’s revolution and rotation • Tilting influences the seasons and temperature changes. Composition of the atmosphere • CO2 and water vapour help to regulate temperatures – the natural greenhouse effect. • Ave temps would be - 18 degrees Celsius if the greenhouse effect did not exist. Distribution of continents and oceans • Warm ocean currents have high rates of evaporation and precipitation. • The cold currents produce little evaporation and precipitation - hence a factor in desert formation. Topography • Orographic rainfall can be produced by mountain ranges. • Moist climates are found on the windward side, while deserts / semi-arid regions are located on the leeward side. Microclimates • What differences would you find between rural and urban areas? Microclimates Urban Rural High temps Lower temps More pollution Less pollution Higher humidity and Less humidity and rainfall rainfall Less sunshine More sunshine Weaker winds Stronger winds Aspect • How can aspect determine climate in an area? Aspect induced microclimates • Sth hemisphere – more sunlight on north facing slopes. Opposite in the Nth hemisphere. • This determines moist / dry slopes as well as bushfire risk and vegetation types. Human interactions with the atmosphere • What are the different ways humans interact with the atmosphere? Interactions • Urban air quality • Acid rain • Greenhouse gases • Ozone depletion Air pollution • Causes 1,400 lung related deaths in Sydney each year – more than car accidents. • However technology is improving – unleaded, diesel, ethanol in petrol, etc. Problem areas • List some cities that have a reputation for serious air pollution. Acid rain • Sulfur dioxide and nitrogen oxide emissions from power plants form acids in the atmosphere that fall to earth as rain, fog, snow or dry particles. • This acid rain is often carried hundreds of miles by the wind. Acid rain damages forests and causes lakes and streams to become acidic, killing the fish. • Acid rain also damages buildings, historical monuments and even cars. Acid rain Acid rain Ozone depletion • Ozone partially filters ultraviolet radiation – UV- B radiation approx 30km above the Earth • Causes: • CFCs in fridges, air conditioners, etc. • Strategies have reduced CFCs considerably. Ozone depletion • Effects: • Ecosystem damage – eg Antarctica: phytoplankton is reduced from increased UV– affects the krill and the rest of the food web.
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