Download 1/12/2012 Chap. 1 - UA Atmospheric Sciences

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1
Chapter 1: The
Earth’s Atmosphere
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Overview of the Earth’s atmosphere
Vertical structure of the atmosphere
Weather and climate
Q: You can live for a few minutes only:
a) without air
b) without water
c) without food
2
Overview of the
Earth’s Atmosphere
• when the earth is scaled to the size
of an apple, 99% of atmosphere is
no thicker than the skin on an apple
• Water vapor molecules are invisible:
clouds;
sink: condensation/deposition
source: evaporation/sublimation/
transpiration (through
vegetation roots)
3
Composition of the
Atmosphere

permanent gases
• Nitrogen
source: decaying of plant and animal matter
sink: soil bacteria;
ocean plankton
• Oxygen
source: plant photosynthesis (sun + CO2 + H2O
lead to sugar and O2)
sink: organic matter decay
breathing (take in O2, release CO2)
Q: which one is larger between the production and destruction
rates: a) production; b) destruction; c) equal
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Q: which is the most important greenhouse gas in the atmosphere?
a) carbon dioxide; b) water vapor; c) methane, d) ozone
380 ppm = 380/106 = 380 * 10-4/102 = 0.038%
5
Composition of the
Atmosphere

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Carbon dioxide and the greenhouse gases
ozone
aerosols
pollutants
• Ozone at high altitudes
(stratosphere) is “good”;
ozone at low altitudes
(troposphere) is “bad.”
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Q: List three
sources and two
sinks of CO2 in
the atmosphere
Q: why is the
global CO2
concentration is
lower in summer
than in winter?
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The Early Atmosphere

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the first atmosphere: hydrogen, helium (most abundant
gases found in the universe)
the second atmosphere through outgassing from the hot
interior (via volcanoes and steam vents):
water vapor,
carbon dioxide, nitrogen
evolution of the atmosphere:
water vapor leads to oceans (via precipitation);
carbon dioxide is dissolved in oceans;
nitrogen is not active chemically;
water vapor is splitted (by energetic rays from the sun)
into oxygen and hydrogen (and hydrogen escapes)
• The evolution of life and the atmosphere are closely
linked.
8
Vertical Structure of the
Earth’s Atmosphere
Rawinsonde is launched twice a day to
measure temperature, humidity, wind, and
pressure of the lowest 30 km above
Surface.
It is called radiosonde if wind is not
measured.
Q: where is the balloon launched
in Tucson? a) airport;
b) Mt. Lemmon, c) UA campus
Q: balloon is released at 00:00 UT
(or GMT). What is the Tucson time?
a) 5am, b) 3pm, c) 5pm
9
A Brief Look at Air Pressure
and Air Density


air density: mass per unit volume
air pressure: air weight (mass times gravity) above a
level

sea-level pressure
• Surface pressure: 1013 mb = 1013 hPa = 29.92 in.Hg
Q: Baseballs travel farther in higher-altitude air (e.g., in
Denver) than they do in lower-altitude air. This
statement is: a) true; b) false, c) undecided.
10
Ps =14.7 psi
=1013 hPa
Q: what is the
typical tire
pressure of
your car?
a) 1Ps;
c) 2Ps;
c) 3Ps
11
Q: what is the
percentage of
O2 at the top
of Mt. Everest
relative to the
sea level value?
a) 13%
b) 23%
c) 33%
d) 43%
12
Layers of the Atmosphere


vertical temperature profile
Troposphere
lapse rate: 6.5oC/1km;
temperature inversion

Stratosphere
O3 absorption


mesosphere
Thermosphere
O2 absorption
13
The Ionosphere

electrified regions of the atmosphere: with
large concentrations of ions and free electrons. Ions are
atoms and molecules that have lost or gained electrons.


D, E and F regions
radio waves
• When the radio was invented
by G. Marconi in the early
20th century, it was not
known how radio waves
traveled long distances
through the atmosphere.
14
AM radio travels farther at night than during the day
15
Weather and Climate
• Satellites
• Radar
• Radiosonde
• Aircraft
• Weather station
See ATMO web site
16
Elements of Weather

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air temperature
air pressure
humidity
clouds
precipitation
visibility
wind
• Certain weather elements, like
clouds, visibility and wind, are
of particular interest to pilots.
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Climate

Statistics of weather, such as
mean values;
mean variations (e.g., seasonal cycle);
extremes
Q: A city’s maximum temperature is 105oF. This
information is related to: a) weather; b) climate;
c) neither; d) either.
Q: Today’s maximum temperature is 75oF. This
information is related to: a) weather; b) climate;
c) neither; d) either.
18
A Satellite’s View of the
Weather

geostationary satellites
• Atmospheric observation
from satellites is an
important technological
development in
meteorology. Other
important developments
include computers, internet,
and Doppler radar.
visible band
19
20
Storms of all Sizes

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midlatitude cyclonic storms
hurricanes and tropical storms
thunderstorms
tornadoes
• Storms are very exciting, but they also play an
important role in moving heat and moisture around
throughout the atmosphere.
Q: based on prior slide, which system is larger?
a) midlatitude cyclonic storm; b) hurricane
21
Doppler radar
22
A Look at a Weather Map

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wind speed and direction
cyclones and anticyclones
fronts
• Wind direction is defined in the opposite way as
ocean currents: a southerly current means water is
moving towards the south.
23
Q: What is the wind direction in Chicago?
a) southerly, b) northerly, c) easterly, d) westerly
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Weather and Climate in our
Lives

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wind chill, frostbite and hypothermia
heat exhaustion and heat stroke
cold spells, dry spells and heat waves
severe thunderstorms and flash floods
• The mathematical formula for determining the wind
chill temperature has recently been revised due to new
experiments.
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Ice storm caused utility poles and power lines to be weighed
down, forcing road closure.
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Tucson, AZ
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