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10.2 Energy Transfer in the Atmosphere Originally, Earth’s atmosphere had no oxygen. Scientists think it first came from the breakdown of water by sunlight,

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Presentation on theme: "10.2 Energy Transfer in the Atmosphere Originally, Earth’s atmosphere had no oxygen. Scientists think it first came from the breakdown of water by sunlight,"— Presentation transcript:

1 10.2 Energy Transfer in the Atmosphere Originally, Earth’s atmosphere had no oxygen. Scientists think it first came from the breakdown of water by sunlight, then from photosynthesis by plants. Scientists think it first came from the breakdown of water by sunlight, then from photosynthesis by plants. The density of the atmosphere decreases with altitude. The composition of Earth’s atmosphere

2 The Layers of the Atmosphere 1)The Troposphere: - closest to Earth’s surface - highest density layer because all other layers compress it - contains almost all the water vapour in the atmosphere. so, this is where most weather takes place. so, this is where most weather takes place. 2 nd warmest layer 2 nd warmest layer See pages 438 - 439

3 The Stratosphere: the second layer the second layer warming from –55ºC as altitude increases warming from –55ºC as altitude increases The air is cold, dry, and cloudless. The air is cold, dry, and cloudless. Strong, steady winds, planes often fly here to avoid turbulent troposphere. Strong, steady winds, planes often fly here to avoid turbulent troposphere. The ozone layer is found here, which blocks harmful UV radiation. The ozone layer is found here, which blocks harmful UV radiation.

4 The mesosphere: (3 rd layer) Temperatures are as low as –100ºC This layer is where space debris burns up when it begins to hit particles. The thermosphere: (4 th layer) Temperatures can reach +1500ºC to +3000ºC because of radiation from the sun This is where the Northern Lights, aurora borealis, are found. The exosphere: (5 th layer) where the atmosphere merges with outer space. The layers of Earth’s atmosphere The Upper Atmosphere

5 Radiation and Conduction in the Atmosphere Thermal energy mostly comes from the Sun. Most thermal energy is transferred near the equator, which receives a more direct source of solar radiation. Most thermal energy is transferred near the equator, which receives a more direct source of solar radiation. Insolation = amount of solar radiation Insolation = amount of solar radiation an area receives, measured in W/m 2 decreases with dust, smoke, pollution, etc. or if the angle of incidence of the solar radiation is too great. Solar radiation does not heat Solar radiation does not heat the atmosphere directly. Earth’s surface absorbs solar radiation, heats up, then radiates the thermal energy into the atmosphere. Convection currents in the air spread the thermal energy around. Angle of incidence

6 The Radiation Budget The radiation budget is used to explain where all of the solar radiation that reaches Earth actually goes. Earth’s radiation budget = heat gained – heat lost Earth’s radiation budget = heat gained – heat lost Of the of the solar radiation that reaches Earth, 15 percent is reflected by clouds back into space, 7 percent is reflected by particles back into space, 20 percent is absorbed by clouds and the atmosphere, and 58 percent reaches Earth’s surface Of the of the solar radiation that reaches Earth, 15 percent is reflected by clouds back into space, 7 percent is reflected by particles back into space, 20 percent is absorbed by clouds and the atmosphere, and 58 percent reaches Earth’s surface 9 percent of this amount is reflected back out into space by Earth’s surface 9 percent of this amount is reflected back out into space by Earth’s surface 23 percent drives the water cycle, 7 percent creates wind, and 19 percent is re-radiated from Earth’s surface. 23 percent drives the water cycle, 7 percent creates wind, and 19 percent is re-radiated from Earth’s surface.

7 The Radiation Budget and Albedo Albedo refers to the amount of energy reflected by a surface. Light-coloured surfaces (snow, sand) have a high albedo and reflect energy. Light-coloured surfaces (snow, sand) have a high albedo and reflect energy. Dark-coloured surfaces (soil, water) have a low albedo and absorb energy. Dark-coloured surfaces (soil, water) have a low albedo and absorb energy.

8 What Is Weather? Weather is atmosphere conditions. related to the transfer of thermal energy. related to the transfer of thermal energy. Atmospheric pressure is determined by the number of molecules and how fast they are moving. measured with a barometer measured with a barometer measured in kilopascals (kPa) measured in kilopascals (kPa) Ex. our ears pop with pressure change as you increase altitude, the pressure drops. as you increase altitude, the pressure drops. Warm air is lighter and less dense than cool air Warm air is lighter and less dense than cool air and so warm air has a lower pressure than cool air. Atmospheric pressure exerts force on you from all directions.

9 Humid air (air with more water vapour) has lower pressure than dry air. Specific humidity = the total amount of water vapour in the air. Specific humidity = the total amount of water vapour in the air. Dew point = the temperature where no more water vapour can be held by air Relative humidity = the percentage of the air that is currently holding water vapour Relative humidity = the percentage of the air that is currently holding water vapour 45 percent relative humidity means that the air is holding 45 percent of the water vapour it could before reaching its dew point.

10 Convection in the Atmosphere Wind is the movement of air from higher pressure to lower pressure. An air mass is a large body of air with similar An air mass is a large body of air with similar temperature and humidity throughout. takes on the conditions of the weather below. can be as large as an entire province or even larger.

11 High pressure systems form when an air mass cools. This usually occurs over cold This usually occurs over cold water or land. Winds blow clockwise around Winds blow clockwise around the centre of the system. Low pressure systems form when an air mass warms. This usually occurs over This usually occurs over warm water or land. Winds blow counterclockwise Winds blow counterclockwise around the centre of the system. Lows usually bring wet weather. Lows usually bring wet weather.

12 Prevailing Winds are winds that are typical for a location. Winds in B.C. usually blow in from the ocean. Winds in B.C. usually blow in from the ocean. Precipitation falls as air is forced up the mountains Precipitation falls as air is forced up the mountains So air gets drier as it moves inland So air gets drier as it moves inland Dry air rushes down the far side of the mountains into the prairies. Dry air rushes down the far side of the mountains into the prairies. See pages 448 - 449 The prevailing winds off British Columbia’s coast, crossing into Alberta.

13 The Coriolis Effect Winds move from higher pressure to lower pressure. In a simple model, air would warm in the tropics and rise. In a simple model, air would warm in the tropics and rise. Cooler air from the north would Cooler air from the north would rush in below to fill the empty spot. The warm air at higher altitudes would The warm air at higher altitudes would move north to replace the cooler air. This occurs at several latitudes as This occurs at several latitudes as we move north. As Earth rotates, these winds are “bent” clockwise = Coriolis effect The equator moves much more quickly than do the poles. The equator moves much more quickly than do the poles.

14 Jet Streams Strong winds occur in areas between high and low pressure systems. The boundaries between the global wind systems have very strong winds. The boundaries between the global wind systems have very strong winds. In the upper troposphere, between warm and cool air, are the jet streams. In the upper troposphere, between warm and cool air, are the jet streams. The polar jet stream can move at 185 km/h for thousands of kilometres. Planes flying east across Canada “ride” the jet stream and avoid it flying west.

15 Local Winds, and Fronts Local winds arise and are influenced by local geography. In British Columbia, sea breezes blow inland when the land warms in the morning and outward when the land cools in the evening. In British Columbia, sea breezes blow inland when the land warms in the morning and outward when the land cools in the evening. A front is a boundary between two different air masses. Cold air forces warm air to rise, so Cold air forces warm air to rise, so fronts usually bring precipitation.

16 Extreme Weather Air masses often have very large amounts of thermal energy. Extreme weather can arise as this energy is released. Extreme weather can arise as this energy is released. Thunderstorms occur when warm air rises and water condenses (which releases even more energy), building the thunderhead even higher. Thunderstorms occur when warm air rises and water condenses (which releases even more energy), building the thunderhead even higher. Static energy can be built up and released as lightning. Sea breezes in the tropics and energetic cold (and even warm) fronts can cause thunderstorms. See pages 452 - 453

17 Tornadoes Vs. Hurricanes Tornadoes form when thunderstorms meet fast horizontal winds. A “funnel” of rotating air may form, which sometimes extends all the way to the ground with winds of up to 400 km/h. A “funnel” of rotating air may form, which sometimes extends all the way to the ground with winds of up to 400 km/h. The tropics, with their intense heat, can often have severe weather. Large masses of warm, moist air rise quickly and cool air rushes in. Large masses of warm, moist air rise quickly and cool air rushes in. Air rotates counterclockwise in the northern hemisphere, clockwise in the south. Air rotates counterclockwise in the northern hemisphere, clockwise in the south. Hurricanes = tropical cyclones = typhoons Hurricanes = tropical cyclones = typhoons Take the Section 10.2 Quiz


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