section D:

atmosphere:

gaseous envelope surrounding earth; composed of a series of concentric layers which extend down into the soil

earth’s atmosphere has what properties?

fluid properties that are constantly changing spatially and temporally (ex: weather)

what keeps the earth’s atmosphere in place?

GRAVITY!! - held to the earth by gravity which creates atmospheric pressure

most of the atmosphere’s mass is…

near the surface

climate is what you ____, weather is what you ____:

expect; get

compare and contrast weather and climate:

they are temporally and spatially different

• weather is here (local area) and now

• climate has a much larger area and much larger temporal periods

composition of the atmosphere: 2 main components

constant/permanent gases and variable/trace gases

constant (permanent) gases: (2)

• more or less same proportion in the lower atmosphere

• made up of 78% nitrogen, 21% oxygen and 1% argon

variable (trace) gases:

• differ in proportion over time and space

• make up less than 1%

• include: water vapour, carbon dioxide, ozone

why is atmospheric water vapour critical? (4)

• it determines the humidity

• source of clouds/precipitation

• absorbs and stores heat energy (most important greenhouse gas)

• move with airflow transporting energy and moderating temperature

atmospheric water vapour varies from…

<1% to 4% by volume (average 2%)

what causes atmospheric water vapour volumes to vary? (2)

• air temperature (warmer air can hold more water vapour than cooler air)

• proximity to large bodies of water

global distribution and variation: water vapour

is the average amount of water vapour in a column of atmosphere in a given month (cm)

global distribution and variation: water vapour patterns (2)

• seasonal (winter/summer) - season temperature changes and the influence it has on water vapour/precipitation absorbs

• land/water contrasts (especially in winter)

carbon dioxide:

CO2 - variable gas - makes up 0.04% of the under 1%

vital functions of carbon dioxide: (2)

photosynthesis and the greenhouse effect

photosynthesis:

plants absorb CO2 and release oxygen and water as by-products

greenhouse effect: (2)

is the trapping of longwave radiation

• warms the atmosphere and therefore the earth

what is the earth’s average temperature? and what keeps it that way?

~15*C - the greenhouse effect!

CO2 enters the atmosphere through ____, and leaves through _____:

a source and a sink

4 CO2 sources:

• volcanic eruptions

• decay of living matter

• respiration

• burning fossil fuels (coal, oil, natural gas)

4 CO2 sinks:

• chemical reactions with rocks

• oceans

• plants (via photosynthesis)

• soil

carbon dioxide concentrations:

have increased >30% in the past 200 years

particulates/aerosols:

minute suspended particles in the atmosphere, existing in both liquid and solid form - derivative of both natural and anthropogenic sources

particulates/aerosols: solid forms

snow, hail, pollutants, soil (dust), smoke, ash, pollen grains, salt spray

particulates/aerosols: liquid forms

clouds and rain

what are 3 functions of particulates/aersols?

• particulates help precipitation to form by acting as condensation nuclei (tiny surfaces for water vapour to condense around)

• particulates absorb or reflect energy which impacts temperature

• also influencing air quality; influencing public health (bad smog days on asthmatics)

hygroscopic:

absorb water - water loving particles (like particulates/aerosols), very important in cloud formation

dust storms in southern alaska: (2)

• scientists first reported major dust storms here in 1911

• dust storms play a role in supplying nutrients (iron) and fuel for phytoplankton booms

what is the significance of high latitude dust storms?

they fuel phytoplankton (the basis for the oceanic food chain) booms

loess:

fine grained sediment created by glacial ice pulverizing rocks

earth’s atmospheric layers can be divided by what 3 properties?

• thermal properties (troposphere, stratosphere, mesosphere, thermosphere)

• composition (homosphere, heterosphere)

• functional properties (ozone layer)

how many thermal layers exist (atmosphere):

4! - troposphere, stratosphere, mesosphere, thermosphere

four thermal layers of the atmosphere are differentiated by: (2)

• temperature changes and gases

• density and composition

sphere:

indicates the entire layer

pause:

indicates a boundary between 2 layers

troposphere: (5)

• lowest thermal/heat layer

• ground level to 10-15km

• upper limit noted by the tropopause

• most active zone

• temperature decreases with increasing altitude

troposphere: activity? (3)

lots and lots of movement heres why:

• majority of nonmarine living organisms

• weather occurs here

• vertical mixing is common (up and down)

environmental lapse rate (ELR): in the troposphere

temperature decreases at an average rate of 6.5*C per 1000m

tropopause: (4)

• the upper limit of the troposphere

• (-57*C)

• 8-18km (average 12km) because the tropospheres thickness varies

• almost all cloud tops end at the tropopause (temperature inversion in the stratosphere)

troposphere thickness: (3)

VARIES!

• higher over equator/thinner over poles

• due to heating/expansion and earth’s rotation

temperature inversions: (4)

reversal of normal temps pattern so that air temperature increases with altitude (in the troposphere)

• opposite of what we expect

• an exception is the ELR (environmental lapse rate)

• significance: traps the heat and pollutants creating worse smog

stratosphere: (7)

• immediately above the tropopause

• between 12-50km altitude

• contains ozone layer that filters UV radiation

• temperature increases with increasing altitude

• stratopause is the upper limit

• commercial jets fly here

• little vertical mixing - slow exchange of gases with troposphere (stagnant)

ozonosphere?

what we often call the stratosphere due to the significance of ozone here

• ozone is 10ppmv (stratosphere) vs 0.04 in troposphere

why does temperature increase in the stratosphere?

because the ozone layer is blocking and absorbing UV radiation, which actively is heating up the ozone layer and the stratosphere as we climb altitude

mesosphere: (5)

• immediately above the stratosphere

• coldest layer

• temperature decreases with increasing altitude

• mesopause is the upper limit (-100*C)

• solar radiation reduces gas molecules to ions (strips an electron to form a positively charged ion)

mesopause marks the…

area where temperature stops decreasing with altitude

what thermal layer has disrupted satellite communications?

mesosphere - due to the solar radiation reducing gases to ions

which thermal layer is responsible for meteor destruction?

mesosphere - burning up rock fragments

thermosphere: (6)

• ‘outerspace’

• uppermost layer (the one that goes out to space - no clear boundary defining when the thermosphere becomes space)

• gases are sorted into a variety of sublayers based on molecular mass

• international space station orbits earth in the thermosphere

• important layer for communication technology

• aurora borealis and australis in this layer

4 important characteristics of the thermosphere:

• temperature increases with altitude (lots of solar radiation - heat)

• intense solar reactions cause molecules to vibrate very fast creating kinetic energy

• particles are super spaced out/far apart

• gases are NOT evenly mixed : heavier on the bottom, lighter on top (heterogeneous composition)

aurora borealis and australis: (3)

• northern and southern lights

• high energy particles emitted from solar wind interact with earth’s magnetic field and emit photons of light

• found mostly near the poles where earth’s magnetic field concentrates solar wind particles

compositional layers: (2)

homosphere & heterosphere

homosphere: (3)

• inner atmosphere

• troposphere, stratosphere, mesosphere

• uniform distribution of gases (even mixing)

heterosphere: (3)

• outer atmosphere

• thermosphere (only)

• gases sorted into layers according to molecular weights

ozone: locations

found in:

1. stratosphere; UV-absorbing ozone layer

2. troposphere; form of pollution (pollutant)

ozone in the troposphere is…

BAD! pollution - increasing and is toxic to plants and people

ozone in the stratosphere is…

GOOD! protects us from harmful UV rays

stratospheric ozone formation:

step 1: UV radiation absorbed by O2 creating free oxygen

step 2: free oxygen combines with O2 to form O3

tropospheric ozone formation:

chemical interaction of sunlight and volatile organic compounds and nitrogen oxides (NOx)

whats causing ozone depletion?

chlorofluorocarbons (CFCs)

chlorofluorocarbons (CFCs): (4)

• are anthropogenic (human-made) pollutants

• they break down O3 into O2 then into ClO (chlorine oxide)

• free Cl damages the ozone layer (100,000 ozone molecules destroyed per Cl atom)

• as the ozone layer is depleted more UV radiation reaches the surface

ozone effects and recovery:

• antarctic ozone hole 1st detected in 1979 (forms every spring in southern hemisphere)

• 1987 montreal protocol - began the CFCs phase-out; since CFCs have been declining with recovery expected by ~2050

impacts of depleted ozone? (4)

increased UV exposure at earth’s surface can cause;

• cancer and suppressed immune systems

• reduced crop yields

• plankton destroyed in oceans (the basis of the food chain…)