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
What is an eddy
A change in the normal/average conditions within the atmosphere. Occur in areas of strong temperature gradient, they warm the cold area and cool the warm area by mixing air
Polar cells
Form as a result of differences in surface temperatures. At the poles cold dense air descends causing an area of high pressure. Coriolis force strongest at poles so air deflected sharply.
Wind belts
Are caused by differences in atmospheric pressure. Air moves from areas of high pressure to low pressure. The greater the difference in pressure the stronger the wind.
The main wind belts:
Polar easterlies Polar front Westerlies Trade winds (NE, SE) Horse latitudes Doldrums
Polar easterlies
Dry cold winds that blow from areas of high pressure to low pressure in the ferrel cells
Polar front
Stationary natural boundary where cold polar air meets warm tropical air and warm moist air rises
Westerlies
Strong winds from the west, tend towards north in northern hemisphere and south in Southern Hemisphere
Horse latitudes
Form under a ridge of high pressure; dry air, little precipitation, variable winds
NE and SE trade winds
Blow towards equator from north and south respectively
Doldrums/inter tropical convergence zone
Area around equator where no winds blow because the warm rising air creates an area of low pressure
Main pressure zones
Polar high/subpolar low pressure belts
Polar front/the poles
Subtropical high pressure belts
ITCZ and the tropics
What are pressure zones
Mark the boundaries of the wind belts
Jet streams
Narrow belts of high speed winds in the upper troposphere. They separate warm air above from cold air below. Form at the boundaries of adjacent air masses with significant differences in temp
Land and sea breezes
Localised weather patterns
Sea breezes
During the day the land warms more rapidly than the water (ocean has higher specific heat capacity). The air above land warms, becomes less dense and rises drawing cooler air landward from the sea
Land breeze
At night land cools faster (lower specific heat capacity). The cool heavy air from the land flows out to sea.
Walker circulation
Arises from trade winds blowing from east to west across the tropical Pacific Ocean carrying moist surface air to the western tropical pacific where the air rises forming clouds
Conduction
Movement of heat from the molecules of one substance to another
Convection
Warm air expands becomes less dense than surrounding cooler air and rises. Cooler heavier air flows toward surface to replace warm air
Radiation
Short wave length radiation (sunlight) is absorbed by the ground and re radiated back out as long wave length radiation (heat/infra red) where the atmosphere absorbs it
Climate
The average weather conditions found in the atmosphere over a long period of time
Weather
The short term atmospheric conditions over a short period of time
Factors that determine earths climate
Solar energy- sun heats earths surface unevenly
Earths tilt- different parts receive different amounts of solar energy at different times
Wind formation- due to convection cells and local conditions
Pressure differences- cause the winds
Coriolis effect- winds and ocean currents deflected clockwise in NH and anticlockwise in SH
How is weather caused
Weather is caused by uneven heating of earths surface by sun so different locations heat up different amounts creating winds that determine whether weather is sunny, rainy or stormy. Weather varies from place to place
Isobars
Join together places with the same air pressure. Flow is clockwise in SH around lows and anticlockwise around highs. Opposite in NH. Closer the isobars, stronger the wind
Isobars measured in
Hectopascals
A front
Marks the boundary between 2 air masses
Cold front
Form when cold air pushes under warmer air ahead of it, forcing the warm air upwards and making cloud and areas of rain. As it passes rain clears but air temp drops and winds change directions
Warm front
Warm air rises over cooler air often bringing prolonged steady rain. As it passes rain becomes patchy but air temp may rise and winds change direction
High isobars
High pressure
Low isobars
Low pressure
Precipitation
Any form of water that moves through the earths atmosphere to its surface. Includes rain, sleet, snow. Rising air gets colder and water vapour in it condenses to form clouds, in areas of high pressure air descends and little precipitation
Anabatic wind
During the day sun warms mountain, air ascends as lighter
Katabatic winds
At night mountain cools air descends as heavier
Two types of jet streams
Polar jets (7-12km altitude) Subtropical jets (10-16km altitude)
How do we know climate is changing?
Increasing temperatures Changes in rainfall Changes in nature Sea-level rising Reduction in arctic sea ice Shrinking ice sheets
Worlds climate varies naturally as a result of:
The way ocean and atmosphere interact with each other
Changes in earths orbit
Changes in energy received from the sun
Changes brought about by tectonic plate movement
What is causing climate to change?
Humans are adding heat-trapping ages to the atmosphere mainly by burning fossil fuels
Green house effect
Earth gets energy from sun in the form of sunlight. Earths surface absorbs energy and heats up. Earth cools down by giving off a different form of energy called infrared radiation. Greenhouse gases in atmosphere absorb some energy making it warmer. Earths surface warmer too.
What are greenhouse gases?
Naturally occurring in the atmosphere: water vapour, CO2, methane, nitrous oxide
Human-made: extra CO2, methane, nitrous oxide and synthetic gases such as fluorocarbons (CFCs and sulfur compounds)
albedo
Measure of the reflectivity of a surface
Evidence earths climate has changed before
Ice cores Fossil pollen Lake sediment Ocean sediment cores Wind borne material Glaciers Tree ring width Instrument measurements and written or oral records
Two conditions that make it likely for a planet to have an atmosphere?
Strong gravity and low temp
What is soil gas and how does it differ from the atmosphere above the soil surface?
Part of the atmosphere in the spaces below the soil surface. Amounts of oxygen and carbon dioxide in soil gas are different from those in atmosphere above soil. Oxygen levels can vary 0-20% and CO2 levels from 0-5%
What is the ionosphere
An area of electrically charged ions in the thermosphere
What causes the temperature gradients in each layer?
The heat sources of each layer
How does a temp gradient between different layers cause winds?
Leads to differences in air pressure between locations and as a result wind, as air particles move quickly from the region of high pressure to that of low pressure
Why are winds stronger in winter?
There is a strong temp gradient between the poles and the equator due to the fact that the poles receive the minimal amount of solar radiation at this time while the equator receives the same amount as at other times of year
Factors that can lead to a change in the atmospheric temp gradient
Altitude, daily heating and cooling changes, seasonal heating and cooling changes, differences between temps of land and water
In terms of particles how decreasing humidity or lowering air temp increases air density?
Decreasing humidity removes water vapour from air, nitrogen that remains has greater mass therefore air has greater density than when water vapour was present. When air temp falls, air particles move slower and come closer together increasing air density
Explain effect of aerosol particles on solar radiation
Aerosol particles can scatter and absorb solar radiation. Different types of aerosol react differently when hit by sunlight.
What is atmospheric circulation
The large scale movement of air masses and the way in which heat energy is distributed around the surface of the earth
What is the main driver of atmospheric circulation?
Unequal heating of the earths surface. Air above equator receives more heat than poles it becomes less dense and rises until reaches tropopause where spreads and moves towards the poles. Cold dense air from poles sinks and moves towards the equator to replace warm air that has risen
What wind belts are created as a result of Hadley cells?
Trade winds
What wind belts are created as a result of ferrel cells?
Westerlies
What wind belts are created as a result of Polar cells?
Easterlies
Pacific Ocean cell
An entirely ocean based cell that’s occurs as a result of marked difference in surface pressures and temps between Easter and Western Pacific Ocean
Motion of air in Pacific Ocean cell
Trade winds blow air east to west across tropical Pacific Ocean
Two phenomena that occur when walker circulation changes
El Niño- trade winds weaken and warm water flows towards Eastern pacific
La Niña- trade winds strengthen causing water in Eastern pacific to be colder than normal
What is pro graphic lifting?
Movement of air up and over a mountain or ridge, causing air to cool as it rises.
Why is water essential part of earths system?
Covers more than 70% earths surface.
Can exist in gaseous, liquid and solid form within narrow range of temp.
Needed by all living things.
Regulates earths temp.
Four key processes in water cycle
Evaporation, condensation, transpiration, precipitation
What is the source of energy that drives the water cycle?
The Sun
How is water added to the atmosphere
Evaporation- solar energy causes water to evaporate from at/near earths surface
Transpiration- evaporation through plant membranes
Explain the link between the oceans and atmosphere in the water cycle
Oceans act as an abundant water source for the atmosphere
Explain the role of the atmosphere in the carbon cycle
Atmosphere major (though small) carbon reservoir for earth acting as both a source and a sink for carbon
What is a carbon flux
Any movement between carbon reservoirs
Difference between biological and physical pumps in carbon cycle
Biological pumps- relate to living things eg. Photosynthesis, respiration, decomposition
Physical pump- does not involve living things eg. Combustion, geological processes, atmosphere exchange