Atmosphere and Weather Review

1. Atmosphere and Weather Review Carlie Bateman Rachel Arkiszewski Olivia Anderson

2. Composition • Nitrogen: 78% • Oxygen: 21% • Water Vapor: 0-4% • Carbon Dioxide: <1%

3. Composition Carbon Dioxide • The volume of carbon dioxide has increased 25% in the last 300 years • Greenhouse gas • Humans are responsible for about 5,500 million tons of carbon dioxide per year • Carbon dioxide stays in the atmosphere for about 100 years Methane • <1% • Greenhouse gas • Increased 150% since 1750 • About 200 million tons are produced naturally per year • Humans contribute another 400 million tons per year • The average methane cycle takes about 10 years

4. Composition Nitrous Oxide • < 1% • Increasing at a rate of about 0.3% per year due to the burning of fossil fuels • Humans are responsible for about 6 million tons per year • Contributes to the Greenhouse Effect • Stays in the atmosphere for about 170 years Ozone • <1% • 97% is found in the first 9-35 miles above Earth’s surface • Absorbs UV radiation • Hole over Antarctica caused by CFC’s • Produced by photochemical smog

5. Structure Troposphere • First 0-7 miles • Contains 75% of the atmospheres mass • Temperature decreases with altitude (up to -76) • Weather is in this layer Stratosphere • Temperature increases with altitude • Ozone is in this layer and is produced by UV radiation and lightning

6. Structure Mesosphere • Temperature decreases with altitude • Coldest layer • Meteors burn up in this layer Thermosphere/ Ionosphere • Temperature increases with altitude due to gamma rays, X rays, and UV radiation • The aurora borealis occurs in this layer

7. Weather and Climate • Weather is caused by the movement or transfer of heat energy • Radiation: flow of electromagnetic radiation • Conduction: collision of 2 heat carrying molecules • Convection: • Driving force in weather. • Pressure differences develop resulting in wind • Without convection the equator would be about 27 F and the Arctic would be about 45 F

8. Factors that Influence Climate • Air mass • Large bodies of air that share similar temperature and moisture content • Equatorial, Polar, Arctic, Tropical, Continental, Maritime • Air Pressure • Gravity on an air mass • Low Pressure: cloudy and stormy weather • High Pressure: contain cool dense air descends towards earth’s surface and becomes warmer and are usually associated with fair weather • Altitude • For every 1,000 ft you rise in elevation, there is a 3 F drop • Albedo • The reflectivity of a surface to solar radiation • Distance to Oceans • Thermally more stable than land • Specific heat of water is 5x that of air • Changes in temperature are more extreme over land than over water • Angle of Sunlight • Areas closer to the sun have higher temperatures

9. Factors that Influence Climate • Clouds • Collections of water droplets or ice crystals in the atmosphere • When droplets get too heavy, they drop • High level clouds are mainly ice crystals • Fronts • The boundary formed by two air masses meeting • Cold Front: leading mass of cold air, associated with thunder and clouds • Warm Front: moisture contained in clouds is released • Carbon Cycle • The consumption of carbon causes cooling • The production of carbon causing heating • Land Changes • Urbanization and deforestation • Heat/ Convection • Hot air rises, cold air sinks • Greenhouse Effect • Without the greenhouse effect, the earth would be too cold to live on • However, if it is taken to far the earth could become too hot to live on

10. Factors that Influence Climate • Landmass Distribution • Oceans absorb solar energy but continents reflect it out • Landmasses at lower latitudes reflect more energy, therefore making the climate cooler • Mountain Ranges • Higher altitudes lead to cooler temperatures • Orographic lifting: air masses are forced from low to high elevations as they move over the terrain; as the air mass rises it expands and cools, possibly causing rain • Rain shadow effect: the side facing the ocean is the windward side and receives more rain • The leeward side is the opposite and it receives little rain • Pollution • From both natural and human sources • Rotation • The earth loses heat at night • Wind Patterns • Convection (rising and cooling) is the primary cause of wind • Global Air Circulation • Caused and affected by: • Uneven heating • Seasons • Coriolis Effect: large scale wind patterns • Convection cells • Amount of solar radiation

11. Factors that Influence Climate: Winds • Anabatic • Develop in the daytime around hilly or mountainous areas • The weather is relatively calm with some sunshine • Air around the hilltops becomes warmer than the air at the same altitude over valleys because it conducts heat from the nearby land surface • Katabatic • Occur during clear nights when the air near the ground loses heat rapidly by radiation • As a result, the air near the ground becomes colder than the air over adjacent valleys • Trade • Prevailing pattern of easterly surface winds found in the tropics • Mainly from the northeast in the northern hemisphere (NE trade winds) • The winds form the southeast in the southern hemisphere are SE trade winds

12. Atmospheric Circulation • Trade winds act as the main force for tropical storms that form horizontal winds that move from areas of high pressure to areas of low pressure • Wind speed is determined by pressure differences between air masses • The greater the difference the greater the wind speed • Wind direction is determined by where the wind is coming from • Winds from the east are called easterly • The prevailing winds from the Northern Hemisphere spiral clockwise out from high-pressure areas

13. AtmosphericCirculation • Hadley Cells • Found around the equator in rainforest climates, Hadley cells produce high humidity, high clouds, and heavy rains • In subtropical regions, they produce low humidity, little cloud formation, and high ocean evaporation • Ferrell Cells • Develop 30-60 degrees north and south of the equator • Winds from Hadley cells diverge and form Westerly’s • Cyclone patterns cause mid-latitude climates to have distinct winters and cool summers • Polar Air Cells • Start as cold dense air, descends from troposphere to the ground, air meets with warm tropical air from mid-latitudes • The air cools and sinks, suppressing the precipitation • Hurricanes • Begin over warm oceans where trade winds converge • A subtropical high pressure zone creates hot day time temps with low humidity that creates large amounts of evaporation • The center of the hurricane is the eye (an area of descending air and low pressure); The energy of the hurricane dissipates over land or if it moves over the cooler bodies of water

14. Atmospheric Circulation El Niño La Niña Trade winds blow west acrossthe tropical pacific and become stronger This leads to an increase upwelling of South America and cooler than normal sea surface temps Unusually cold temps in eastern equatorial pacific Brings the opposite effects than El Nino to the US A substantial increase in hurricanes Responsible for heavier than normal monsoons in India and Southeast Asia • When pressures in the south pacific reverses directions, the trade winds decrease in strength • The result is that normal flow of water away from South America decreases and ocean water piles up off South America • This pushes the thermocline deeper and decreases the upwelling of nutrient rich water Sea surface temperatures increase in the eastern pacific • The net result is a shift of prevailing rain pattern from the normal western pacific to central pacific