The Atmosphere and Space

1. The Atmosphere and Space

2. The Atmosphere The atmosphere is the layer of air surrounding the Earth. The air is a gaseous mixture mostly made up of nitrogen(78%) and oxygen (21%).

3. Pressure is defined as the amount of force per unit of area. The pressure for a gas is dependant on the number of collisions it undergoes. Two factors affect atmospheric pressure: • The number of air particles. As the number of air particles increases, the number of collisions increases. Air pressure decreases as we move up into the atmophere. 2. The air temperature. As temperature increases, gases move faster, increasing the number of collisions. Warm air is less dense than cold air.

4. Atmospheric Circulation The movement of the layer of air surrounding the Earth is known as atmospheric circulation. The rotation of the Earth changes the direction of the air masses through the Coriolis Effect. It causes the winds in the troposphere to deviate to the right in the Northern hemisphere and to the left in the Southern hemisphere.

5. EST The Coriolis effect creates circulation cells in which the air masses form “loops”. Heat is circulated through these cells. Each hemisphere has three circulation cells: • Hadley cell: from the equator towards the 30th parallel • Ferrel cell: from the 30th parallel to the 60th • Polar cell: from the 60th parallel to the poles

6. EST Prevailing winds The prevailing winds in each hemisphere move the air from east to west (or west to east). • Polar easterlies move between the pole and the 60th parallel • Westerlies move between the 60th and 30th parallel • Trade winds move between the 30th and the equator.

8. Air Masses An air mass is a large part of the atmosphere with a uniform temperature and humidity. Air masses can be warm or cold. Warm front: warm air mass meets a cold air mass. This results in the warm air rising gently, producing light winds and rain. Cold front: cold air mass meets warm air mass. This results in warm air rising rapidly above the cold air, producing wind and heavy rain.

9. Anticyclones and Depressions When air masses move vertically, they create anticyclones or depressions. When cold air falls, it creates a high pressure zone (H) known as an anticyclone. This results in clear skies and dry weather. When warm air rises, it creates a low pressure zone (L) known as a depression. This results in cloud formation and rain.

10. The Greenhouse Effect The Earth’s atmosphere plays an important role in retaining the Sun’s heat. Greenhouse gases (H2O, CO2, CH4 and NO2) trap some of the infrared rays and send them back to the Earth. The increased use of fossil fuels (combustion) has led to an increase in the quantity of CO2 in the atmosphere.

11. Other activities such as digestion in farm animals and the use of nitrogen-rich fertilizers contribute to the Greenhouse effect. Due to the increase in greenhouse gases, there have been abnormal modifications to the Earth’s climate.

13. EST Contamination Other contaminants degrade the atmosphere: • Sulfur dioxide, SO2, and nitrogen oxides, NOx, contribute to acid rain and smog formation. • Heavy metals released through combustion are toxic to human health • Chlorofluorocarbons, CFC’s, destroy th ozone layer • Dust discharged from combustion

14. EST The Ozone layer is responsible for absorbing the harmful UV rays from the sun. An increase in the number of CFC’s in the atmosphere are responsible for the thinning of the ozone layer. Smog is a thick layer of smoke and fog. Smog appears over urban areas when a high pressure system is present.

15. Energy resources Wind energy is the primary energy resource from the atmosphere. It is considered a clean form of energy can be used to turn wind turbines. However, wind speed and occurrence is unpredictable and its energy cannot be stored unless a turbine is used.

16. Effect of the Sun & Moon on the Earth The Sun and the Earth’s Moon have important effects on the planet. The Sun radiates its warmth and light onto the planet. The Earth’s Moon exerts a gravitational force on the planet and this affects the movement of the tides.

17. Solar Radiation The Sun’s high temperature causes nuclear reactions to occur in its core, where hydrogen is transformed into helium through fusion. The energy that is produced through the nuclear reactions is carried by electromagnetic waves and creates light and heat.

18. The heat that makes its way to our planet heats the atmosphere, oceans and land. Because of the tilting of the planet on its axis, some regions receive more heat than others.

19. Solar energy can be harnessed and put to use through: • Passive heating systems. This type of system involves the correct positioning of a house or building to make the most of the Sun’s rays. • Photovoltaic cells. Used in solar panels, these cells are usually made up of silicon. When the light energy hits the electrons in the cells, they are set in motion (electrical current).

20. Earth-Moon System The Moon’s mass is large enough to have an affect on the Earth. The gravitational pull affects the movement of the tides. The Moon’s pull will pull the Earth’s water towards it.

21. When the Sun and the moon are aligned, the pull on the Earth’s water is especially great. This creates high tides known as Spring tides. Tidal power can be harnessed through power plants. While the movement of tides can be predicted, the plants are costly and have to withstand harsh salt water conditions.