1. Weather & Climate
What is “climate”?
Climatology for Bozeman MT
Lat=45.5N
at 5 5 Lon=111.1W
o
Elevation=4467
e at o
6 feet
eet
Number of years available from 1961 to 1990: 30
Maximum temperature 1961 to 1990: 103 F
Minimum temperature 1961 to 1990: -46 F
Mean Annual Precipitation: 14.7 inches
Mean Annual Snowfall: 44.4
44 4 inches
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http://www.cdc.noaa.gov/cgibin/USclimate/city.pl?state=MT&lane=fast&itypea=1&loc.x=237&loc.y=199&.cgifields=itypea
3. Reading Weather Maps
http://www.montana.edu/mcwethy/ERTH303/
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3. Reading Weather Maps
3
http://www.opc.ncep.noaa.gov
3. Reading Weather Maps – station data
http://www.montana.edu/mcwethy/ERTH303/
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3. Reading Weather Maps – station data
Weather:
Sky Conditions:
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3. Reading Weather Maps – station data
Wind:
Pressure Trend:
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3. Reading Weather Maps
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http://www.opc.ncep.noaa.gov/UA/USA.gif
Weather and Climate News
• Does it feel unusually cold?
National Water and Climate Center
ƒ temperature
ƒ precipitation
ƒ snow
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Composition and Structure of the
Atmosphere (ERTH 303, 3 September, 2009)
1. Composition
a.
b.
c.
The atmosphere
Permanent gases
Variable gases
2. Vertical
Structure
a.
b.
c.
Temperature
Electrical properties
Function
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1. Composition of the Atmosphere
≈ 100 km
≈ 12 km thunder heads Æ
Where does Earth’s
Earth s atmosphere end?
100 km Æ 99.99997%
2% of Earth’s thickness
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Photo from NASA: http://eobadmin.gsfc.nasa.gov/Newsroom/NewImages/images.php3?img_id=17542
inp
put rate
Physical Processes:
• chemical reactions
• volcanic eruptions
Biological Processes:
• photosynthesis
p
y
• respiration
• human activity
output rrate
1. Composition – components cycle
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Photo from NASA: http://eobadmin.gsfc.nasa.gov/Newsroom/NewImages/images.php3?img_id=17542
1. Composition (and some structure)
Permanent Gases (homosphere: 0-80 km alt.)
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Aguado and Burt, Table 1-2.
1. Composition (and some structure)
Variable Gases
Methane
CH4
0.00017
76.01
ƒ Low abundance, but very important
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Aguado and Burt, Table 1-3, with Methane added.
1. Composition
Water Vapor
ƒ
ƒ
ƒ
ƒ
ƒ
Gas molecules (not liquid), source for cloud formation
Radiative forcing = ++
Created by evaporation
Removed by precipitation
Residence time = 10 days
clouds
water vapor
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http://wwwghcc.msfc.nasa.gov/GOES/goeseastconuswv.html - 1 September, 2008
1. Composition
Carbon Dioxide
ƒ Radiative forcing = +
ƒ Input: respiration,
organic
i d
decay, volcanic
l
i
eruptions, anthropogenic
activity
ƒ Uptake: photosynthesis
ƒ Residence time =
150 yr
From the Mauna Loa Observatory: http://www.mlo.noaa.gov/home.html
1. Composition
Methane
ƒ Radiative Forcing = +
ƒ Input: wetlands, termites,
anthropogenic
th
i activity
ti it
ƒ Uptake: soils,
Atmosphere
ƒ Residence time =
10 yr
http://www.esrl.noaa.gov/gmd/ccgg/iadv/
1. Composition
Ozone
ƒ Radiative Forcing
g=+
(nearby), − (up high)
ƒ Input: chemical
reactions involving
ultraviolet radiation
ƒ Destroyed via
chlorine containing
chlorine-containing
compounds chlorofluorocarbons
http://www.epa.gov/air/oaqps/gooduphigh/
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1. Composition
Ozone-depleting chemicals:
100 yr lifetime (effective equivalent chlorine - EECl)
year
NOAA Earth Systems Research Lab: http://www.esrl.noaa.gov/gmd/hats/graphs/graphs.html
1. Composition
Ozone-depleting chemicals:
100 yr lifetime (effective equivalent chlorine - EECl)
http://toms.gsfc.nasa.gov/multi/ozone_time_series.jpg
What is a DU? – Dobson Units
1. Composition
Ozone-hole
http://toms.gsfc.nasa.gov/multi/ozone_time_series.jpg
What is a DU? – Dobson Units
2. Vertical Structure – via function
Ozonosphere:
ƒ maximum ozone concentrations (20-30 km)
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http://ozonewatch.gsfc.nasa.gov/index.html
August 30th, 2009
Weather and Climate News
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NYT Link: http://www.nytimes.com/2008/09/04/science/04cyclone.html?ref=science#
Nature Link: http://www.nature.com/nature/journal/v455/n7209/pdf/nature07234.pdf
1. Composition
Aerosols (aka particulates)
ƒ Small ((0.1 μ
μm radii),
),
function as condensation
nuclei
ƒ Radiative forcing = −
ƒ Input: sulfate conversion,
dust, volcanoes, sea
spray, combustion
ƒ Removed by precip.
ƒ Residence time = days
to weeks
k to months
h (if in
stratosphere)
MT
ID
WY
Fires in Idaho and Montana producing visible aerosols,
August 7,
7 2000.
2000 Source: NASA Visible Earth project
http://visibleearth.nasa.gov/view_rec.php?id=676
Composition and Structure of the
Atmosphere
1. Composition
a.
b.
Permanent gases
Variable gases
2. Vertical
Structure
a.
b.
c.
d.
Density
Temperature
Electrical properties
Function
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2. Vertical Structure – via density
den
nsity (kg / m3)
Density = mass per unit volume
Aguado and Burt Fig. 1-8. Because air is
compressible and subjected to greater
compression at lower elevations, the
density of the air at lower levels is greater
than that aloft.
Mean free p
path =
average distance traveled before colliding with another
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molecule. e.g. 0.0001 mm at 0 km asl vs. 1 km at 250 km asl
2. Vertical Structure – via temp.
Why temperature?
Wh
t
t
?
ƒ temperature impacts how easily air moves vertically
(details revealed in Chapter 6)
Standard Atmosphere =
models defining atmospheric variables as a function of
altitude, for a given set of mean conditions at sea
level
For example, the U.S. definition of “standard atmosphere” is described or defined in the following web sites:
http://en.wikipedia.org/wiki/U.S._Standard_Atmosphere
http://modelweb.gsfc.nasa.gov/atmos/us_standard.html
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2. Vertical Structure – via temp.
Thermosphere
(“thermos” = heat)
ƒ T increases with alt., to > 15,000°C
ƒ little
littl h
heat,
t b/
b/c low
l
d
density
it
Mesosphere (“mesos” = middle)
ƒ T decreases with alt.
ƒ 99.9% of remaining atm.
Stratosphere (“strato” = layer)
ƒ T increases with alt., little vert. motion
ƒ 19.9% of atm.
ƒ ozone “layer”
y
between 20-30 km ((10 pp
ppm))
Troposphere
(“tropos” = turn)
ƒ T decreases with alt.
ƒ 80% of atm. by mass
ƒ depth varies (8-16 km, mean 11 km)
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2. Vertical Structure – via temp.
¾ Mesospause
¾ Stratopause
¾ Tropopause
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2. Vertical Structure – via electrical properties
Ionosphere:
ƒ defined by electrical properties
ƒ reflects
fl t AM radio
di waves
ƒ responsible for aurora
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http://en.wikipedia.org/wiki/Ionosphere
QUIZ #1
Name
Date
Class
(1) Why is the ozone layer important?
It blocks harmful shortwave radiation yet allows long-wave
long wave radiation to reach the
earth’s surface which supports biological processes (photosynthesis)
(2) What is the difference between water vapor and visible clouds?
W
Water
vapor is
i a gas and
d visible
i ibl clouds
l d are made
d up off liliquid
id molecules
l
l
(condensed water vapor.
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QUIZ #1: Answers
(3a)
1. (Right plot) what is the atmospheric pressure associated with the High in MT?
1023
2. Where is there a low pressure trough? NE MT or S. Idaho
(3b) (Left plot) what is the wind direction and approx. speed? 5 knots
1. (left plot) what is the atmospheric pressure? 1018.5
2. (left plot) what is the atmospheric pressure trend? Decreasing then stable
3 (left plot) what is the sky cover? clear
3.
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Weather and Climate News
Global temperature anomalies: 1881-2008
2008 was coolest
l t yr. since
i
2000 but
b t ninth
i th warmestt since
i
1881 (2005
1st, 2007, 2nd)
http://svs.gsfc.nasa.gov
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