Atmospheric Processes Flashcards
Atmosphere composition
Nitrogen 78%
Oxygen 21%
Trace gases 1% (carbon dioxide, ozone)
Importance of the atmosphere
Most organisms need oxygen for respiration
Traps heat, providing suitable temp for life, prevents heat radiating out space
Transmits sounds
Protection against objects from outer space
Part of water cycle
Transfers heat around earth
Supports flying insects and birds
Plants, algae and Cyanobacteria need CO2 for photosynthesis
Protects living organisms from harmful UV radiation
Troposphere (7)
Weather occurs in this layer (unstable, convection currents) as most water vapour and dust
Contains 75-80% of the mass of the atmosphere
7-30 km above sea level
15 to -57 degrees Celsius temp decrease with altitude
Jet stream just below tropopause
Volcanic ash doesn’t stay very long
Air pressure and density decrease with altitude
Wider at equator, narrower at poles
Stratosphere (5)
Jet air crafts fly in this layer (Stable, very dry with little water vapour therefore no weather)
Ozone layer absorbs harmful UV rays, re-radiate energy as hear warming stratosphere -extends from 15-35 km above sea level
50 km high
Temp rises with altitude
Volcanic ash and dust stay here for a long time
Mesosphere (4)
Meteorites burn up in this layer
50-85 km high
As low as -120 degrees Celsius top layer, temp gets colder with altitude because air thin/molecules far apart doesn’t absorb solar energy
Noctilucent clouds form over the poles
Thermosphere (6)
Auroras
International space station orbits
90-500 and 1000 km high
Temp rises sharply in lower thermosphere due to solar heating
Upper thermosphere temps can range from 500-2000 degrees Celsius, however feels cold because hot gas particles (O, H, He) far apart
Hotter in day than night
Exosphere (4)
Satellites/space shuttle orbit
10,000 km and above
Very thin as few atmospheric particles (atoms and molecules) escape into space
H and He main components
How is ozone created
When high energy ultraviolet radiation from the sun strikes an oxygen molecule, converting it to ozone O3
How are auroras created
By the collision of charged particles and solar wind which become directed into the the atmosphere by earths magnetosphere. Charged particles she’s excess energy which produces colour auroral displays
Atmosphere
A layer of gases surrounding a planet, held in place by the gravity of the planet
What is atmospheric temperature gradient
The rate and direction of change of temperature in a particular location ie. in some layers the temperature increases with altitude while in others it decreases
Describe atmospheric pressure
The force exerted by air on a certain area
What is atmospheric pressure gradient
The rate and direction of change of air pressure at a particular location
Describe atmospheric density
Is the mass of air molecules per unit of volume
Aerosols
Are minute solid and liquid particles suspended in the atmosphere
3 main types of aerosol affect the earths climate
Volcanic aerosols
Desert dust
Human-made aerosols
Volcanic aerosols
Volcanic aerosol layers form in the stratosphere after major volcanic eruptions. Sulfur dioxide gas is converted to droplets of sulfuric acid in the stratosphere for up to several months after the eruption. Winds spread aerosols around the globe. Stay in stratosphere for 2 years. Reflect sunlight, reducing amount of energy reaching lower atmosphere and earths surface, cooling the earth
Desert dust
The particles in dust plumes are minute grains of dirt blown from the desert surface. Relatively large and blown to high altitudes by intense dust storms.
Composed of minerals so particles absorb sunlight as well as scatter it, warming the layer of the atmosphere they are in
Human-made aerosols
Aerosols form from smoke from the burning of tropical rain forests and fossil fuels. Sulfate aerosols survive in atmosphere for 3-5 days, reflect sunlight reducing amount of radiation reaching earths surface
Clouds
Are visible masses of liquid droplets or frozen crystals made of water suspended in the atmosphere above earths surface
Removal of aerosols
Mainly removed from atmosphere by rain
Different layers of the atmosphere
Troposphere Stratosphere Mesosphere Thermosphere Exosphere
Earths atmosphere
A very thin layer of gases held in place by gravity
Nacreous clouds
Stratosphere very dry as little water vapour, very few clouds except PSCs (nacreous clouds) which appear in lower stratosphere near the poles in winter when temp is below -78 degrees C. They help form the ozone hole by encouraging certain chemical reactions to occur that destroy ozone
Temperature is measured in
Kelvin, K or degrees Celsius
Pressure is measured in
Millibars, mb or hectopascals, hPa or pascals per metre, Pa/m
Horizontal temperature gradients
Absorption of solar radiation at or near the earths surface can lead to a change in temperature gradient that can lead to convection. To reduce the large temperature difference between the poles and the equator the atmosphere and ocean re distribute masses of warm and cold air
Horizontal pressure
Unequal heating of the earths surface creates pressure differences. The air is warmer at the equator than at the poles. Warm air has low pressure, cool air has high pressure. Winds blow from high to low pressure. The closer together the isobars are the greater the difference in pressure and the stronger the winds are
Atmospheric density measured in
Kilograms per cubic metre, kgm-3
Atmospheric density decreases with
Increasing altitude (fewer particles) Increased temperature (warmer particles moving faster + further apart) Increased humidity (extra water vapour has a smaller mass than dry air for the same volume)
Earths tilt
23.5 degrees
Summer in the Southern Hemisphere
Sun directly over Tropic of Capricorn once a year on the 21/22 dec -summer solstice
Summer solstice in Southern Hemisphere degrees
Arctic circle (66.5)- 24 hours darkness Tropic of Cancer (23.5)- 13.5 hours Equator (0)- 12 hours darkness Tropic of Capricorn (23.5)- 10.5 hours Antarctic circle (66.5)- 0 hours darkness
Winter Southern Hemisphere
Sun is directly over the Tropic of Cancer once a year on the 21/22 June - summer solstice in Northern Hemisphere
Summer solstice in Northern Hemisphere degrees
Arctic circle (66.5)- 24 hours daylight Tropic of Cancer (23.5)- 13.5 hours Equator (0)- 12 hours daylight Tropic of Capricorn (23.5)- 10.5 hours Antarctic circle (66.5)- 0 hours daylight
Equinoxes
Sun directly overhead at the equator twice a year on the 21st March and 21st September
Aerosols and sunlight
When particles sufficiently large, we notice their presence because they scatter and absorb sunlight.
Eg. Smoke from Australian bush fires scatter sunlight, reduce visibility forming a haze
Aerosols and the climate
Aerosols help form clouds, which have an impact on climate
Aerosols and air pollution
Some aerosols form naturally, while people release others into the air. Breathing aerosols from air pollution can make people ill
Aerosols and chemical reactions
Aerosols can act as sites for chemical reactions to take place. During winter in polar regions aerosols form polar stratospheric clouds. The large S.A of the cloud particles provides sites for chemical reactions. The reactions can lead to the formation of large amounts of chlorine which ultimately leads to the destruction of ozone in the stratosphere
How do clouds form
Water vapour and aerosols bump into each other. Warm air contains more water vapour than cool air. When the air cools to its dew point, some water vapour sticks to the aerosols when they collide and condenses to liquid water. These water droplets start sticking together with other droplets, forming clouds
Atmospheric circulation
Is the large scale movement of air masses and the method by which heat energy is distributed around the surface of the earth
Hadley cells
Strongest of the 3 cells of circulation and form as a result of warm moist air rising above the equator and flowing northward or southward. The rising air creates a band of low pressure at the equator. Northward flow deflects to the right in northern hemisphere due to coriolis effect. As the air moves towards the poles it cools and sinks producing a band of high pressure called the subtropical high
Ferrel cells
Are not closed loop convection cells because don’t have heat source of the equator or cold heat sink of the poles to drive convection. Can be affected by passing weather systems. Have air rising where it is relatively cold and sinking air where it is relatively warm because of eddies