Section D: Earth's Atmosphere

what is the atmosphere

a gaseous envelope surround earth, a series of concentric layers

how is the atmosphere held to the earth

by gravity

where is most of the atmosphere’s mass

near the surface

what is weather related to the atmosphere

fluid properties that are constantly changing spatially and temporally

how is constant (permanent) gas distributed in the atmosphere

more or less same proportion in the lower atmosphere

what is the constant (permanent) gas made up of

78% nitrogen, 21% oxygen, 1% argon

how does variable (trace) gases differ

differ in proportion over time and space

what are variable (trace) gases made up of and how much

they make up less than 1%: water vapour, co2, ozone, helium, neon, methane

why is water vapour important and how does it affect temperature

it determines the humidity and is a source of clouds/precipitation

what is the most important greenhouse gas and why

water vapour because it absorbs and stores heat energy (movement of energy)

how much does the percentage of water vapour vary

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

what does the variation of water vapour depend on

air temperature (warmer air holds more water vapour than cooler air) and proximity to large bodies of water

what is global distribution and variation

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

what are the global distribution and variation patterns

seasonal (summer/winter) and land/water contrasts (especially in winter)

greenhouse effect

trapping of longwave radiation (warms the atmosphere which warms the earth)

what is earth’s temperature

15°

photosynthesis

plants absorb co2 and release oxygen and water as a by-product

what is carbon dioxide’s climatic influence

0.04%

what would happen without water vapour in the atmosphere

the earth would be -15°C because there wouldn’t be anything to trap the heat

what are co2 sources examples

volcanic eruptions, decay of living matter, respiration, burning of fossil fuels (coal, oil, natural gas)

what are co2 sinks examples

chemical reactions with rocks, oceans, plants, soil

by how much do co2 concentrations increase every year

2 parts per million every year

particulates/aerosols

minute suspended particles in the atmosphere, existing in both solid and liquid form

examples of solid particulates

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

examples of liquid particulates

clouds and rain

how do particulates help precipitation

they form by acting as condensation nuclei, they are tiny surfaces for water vapour to condense around

hygroscopic

absorb water, water loving

how do particulates affect temperature

they absorb and reflect energy

how do particulates influence air quality

they affect public health and those with copd or asthma

how do dust storms play a role in southern alaska

they supply nutrients (iron) into the gulf of alaska and provide fuel for phytoplankton blooms which are the foundation of the aquatic food web

what are the thermal properties of the atmosphere

troposphere, stratosphere, mesosphere, thermosphere

what are the compositions of the atmosphere

homosphere, heterosphere

what are the function properties of the atmosphere

ozone layer

how are the thermal layers divided

by temperature changes and gases, in density and composition, and sphere and pause

when we say “sphere” what is that including

the entire layer

when we say “pause” what is that including

the boundary between 2 layers

what is the lowest thermal layer

the troposphere

what is the most active zone and why

the troposphere because there is lots of movement from weather and vertical mixing in and out of the atmosphere

what happens to the temperature in the troposphere

the temperature decreases with increasing altitude

what is the environmental lapse rate

the temperature decreases at an average rate of 6.5°C per 1000m or 1km

what is the tropopause and what is it’s thickness

the upper limit of the troposphere, 8-18km

why does the thickness of the tropopause vary

it’s higher at the equator because the hotter air rises and expands and causes the equatorial bulging

what is temperature inversion

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

normal or temperature inversion

normal

normal or temperature inversion

temperature inversion

where does the stratosphere reside

immediately above the tropopause

what does the stratosphere contain

the ozone layer

what is the general range of the stratosphere

12-50km altitude

what is the ozone in the stratosphere compared to in the troposphere

10 ppmv vs 0.04

how does the temperature change in the stratosphere and why

the temperature increases with increasing altitude because of the ozone absorbing UV rays

what is the upper limit of the stratosphere

the stratopause

where do commercial jets fly and why

in the stratosphere where there is less turbulence because of little vertical mixing

where does the mesosphere reside

immediately above the stratosphere

what is the coldest atmospheric layer and how cold can it get

the mesosphere, upper limit = -100°C

what happens with the temperature in the mesosphere

temperature decreases with increasing altitude

what happens in the mesosphere

solar radiation reduces gas molecules to ions (strips an electron to form a positively charged ion) which disrupts some satellite communication

what is the uppermost layer

the thermosphere

what happens to the temperature in the thermosphere

temperature increases with altitude

why is it so hot in the thermosphere

intense solar reactions cause molecules to vibrate at very high speeds which creates kinetic energy

which layer does the international space station orbit in

the thermosphere

how are the gases sorted in the thermosphere

into a variety of sublayers based on molecular mass

what is the density like in the thermosphere

low density

how are the northern and southern lights created and where

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

homosphere

the inner atmosphere where there is a uniform distribution of gases (even mixing)

heterosphere

the outer atmosphere (thermosphere) where the gases are sorted into layers according to molecular weight

where is ozone found and its role

stratosphere - the uv absorbing ozone layer, and the troposphere - in the form of atmospheric pollution (toxic to plants and people)

stratospheric ozone steps

1. uv radiation is absorbed by O2 which creates free oxygen

2. free oxygen combines with O2 to form O3

tropospheric ozone

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

chlorofluorocarbons

anthropogenic pollutants - synthetic chemical

how do CFCs affect ozone

they go into the stratosphere where uv rays break a chlorine atom away from it. it then reacts with O3 and breaks it into O2 and a free oxygen. the free oxygen reacts with the chlorine to form chlorine oxide which damages the ozone layer