atmosphere
- Created by: LU,KTGFVW
- Created on: 31-03-17 10:07
atmosphere
the atmpsphere is a mixture of gases surroinding the earth
- nitrogen (78%) and oxygen (21%) are the most common
the upper limit of the atmosphere is thought to be between 100 and 120km
there are different layers in the atmosphere
- troposphere
- stratosphere
- mesophere
- thermosphere
- exosphere
the troposhpere
the troposhpere is the lowest layer of the atmopshere and has most of its mass (75-80%)
it extends upwards about 10km above sea level
99% of the water vapour in the atmosphere is found in the troposphere
air pressure and temperature decrease as you go up the troposphere
the boundary between the troposphere and the next layer is the tropopause
the stratosphere
the stratosphere is the second layer of the atmosphere
the bottom of the stratophere is about 10km and the top of the stratosphere is about 50km
the oxone layer is found in the statosphere (ozone is O3)
few clouds are found in this layer the only ones are Polar Stratospheric Clouds
- found in altidues of 15-25km and when the temperature is below -78 degrees C
lots of materials are found in the stratophere stay there for a long time due to the lack of vertical convection
temperature increases as you go up the stratosphere
the area between the stratosphere and the next layer is the stratopause
the mesosphere
the mesosphere is above the stratosphere and extends from 50-85km above the surface
the temperature decreases in the mesosphere and the coldest temperature in the atmosphere is found here (about -90 degrees C)
most of the meteors vaporize in the mesosphere, becuse of this it has a high consntration of iron and other metal particles
clouds called 'noctilucent clouds' and 'polar mesospheric clouds' form here
eletricl discharges are called sprites and ELVES
the air pressure at the bottom of the mesosphere is 1% of the pressure at sea level
the area between the mesosphere and the next layer is the mesopause
the thermosphere
the thermosphere is above the mesosphere and extends about 90-500km above the surface
temperatures increase in the thermosphere and can get up top 500 degrees C
- the reason for the high temperature is the UV rays is absorbed there
the air density in the thermosphere is so low it is norrmally theought of as space
most statlites orbit in the thermosphere
the aurora (northern lights) occur in the thermosphere
the area between the thermosphere and the next layer is called the thermopause
the exosphere and ionosphere
the exosphere is considered by some scientists to be the final layer of the atmosphere
- air in the exosphere is actually leaking into space at a very slow rate
- the top of the exosphere is somewhere between 100000-190000km above the surface
the ionosphere is a region in the mesosphere and thermosphere
- it is where high-energy radiation from the sun makes molecules into isotopes by knocking lose electrons from their atoms and molecules
climate
regional climate is the climate where you live - it is the average weather in a place for more than 30 years
the climate is effeted by the amount of sunlight that an area recieves, its altitude, the shape of the land and how close it is to sea level
global climate is a decription of the climate of the whole planet
the amount of solar radiation, chemistry of the atmosphere and the biosphere all effect the earths climate
climate change
the sun:
- the change in the cycle of the sun effects the climate
- over tens of thousands of years the earths orbit around the sun changes effecting the amout of solar radiation absorbed by the earth
volcanic eruptions:
- when volcanoes erupt the release particles into the atmosphere- the main one effecting the climate is sulfer dioxide
- it gets into the atmosphere and refelects solar radiation - the effects is only temperary
greenhouse gases:
- make up less then 1% of the atmosphere but trap a lot of heat
- over the last 150 years the amount of greenhouse gases has increased through the use of fossil fuels and changing landscapes
weather
weather is different in different parts of the world and changes over time
the weather events are controlled by changes in air pressure.
- when there is high pressure the skys are normally clear
- when there is low pressure it tends to be cloudy
meteorologisits predict the weather through monitoring changes in pressure and weather conditions in the surrounding area
it is hard to predict the weather far in the future becuase of the chaotic nature of the atmosphere
air pressure
air pressure varies on the earths surface. areas where the air is warmed often have low pressure are are called low pressure systems. areas with high pressure are called high pressure systems
low pressure systems:
- winds blow towards areas of low pressure
- as the air rises, the water vapour condencing forming clouds and precipitation
- the coriolis effect causes low pressure to to turn anti-clockwise in the northern hemisphere
high pressure systems:
- wind blows away from high pressure systems
- air from higher in the atmosphere sinks down to fill the space left as the air is blown outwards
clouds
clouds form when the air cools below dewpoint, and the air cannot hold much water vapour
clouds are made of water droplets or ice crystals that are so light that are able to stay in the air
some clouds form when air heated by the ground rises. when it gets to a certain altitude the water vapour condences to form a cloud. he types of cloud formed are cumulus, cumulonimbus, mammatus and srtatocumulums clouds
another way that clouds form is when wind is forced upwards when it hits a mountain. as the air rises the water vapour condences forming clounds. the types of cloud formed are lenticular, stratus and cumulus clouds
at a warm front clouds form when the less dence warm air is foced above the cold air mass forming clouds. the types formed are are altocumulus, altostratus, high cirrus, cirrocumulus, cirrostratus, cumulonimbus and nimbostratus clouds
atmospheric circulation
air in the atmosphere moves around in a pattern called the global atmospheric circulation
it forms 3 main cells on each side of the equator
- the hadley cell
- the ferrel cell
- the polar cell
the hadley cell is at the equator until about 30degrees north of south
the ferrel cell is from 30 degrees until 60 degrees
the polar cell is from 60degrees until the poles
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