Download Water in the Atmosphere

Water in the
Atmosphere
Earth Science/Geology
Mr. Traeger
We must understand the properties
of water in order to understand how
it behaves in the atmosphere.
The structure of
water looks like
“Mickey Mouse.”
Two Hydrogens
and One
Oxygen bond to
make H2O.
We must understand the properties
of water in order to understand how
it behaves in the atmosphere.
Water molecules
bond in hydrogen
bonding where
the positive
hydrogen bonds
with the negative
oxygen.
This bonding of molecules allows
for changes of state of water.
Water molecules
bond in hydrogen
bonding where
the positive
hydrogen bonds
with the negative
oxygen.
Water is the only
substance that commonly
exists in all three states of
matter. This is solid, liquid,
and gas (Spaulding, 390).
Here are the
states of water.
See page 391 in
your book for a
better diagram.
Note where heat
is released and
where heat is
absorbed.
Remember when we heated water from
ice to water to steam? This is the graph
that we did in class.
Phase Changes of Water
120
Energy goes into
evaporation of water.
100
99
98
99
Temperature in Deg. Celsius
87
Energy goes into
heating water from
melting point of zero
degrees Celsius to 64
boiling point of 100
degrees Celsius.
80
60
45
40
20
Energy goes into melting
ice.
12
0
2
0
0
18
3
8
10
13
15
Time in Minutes
18
19
23
25
Notice how water goes through phase
changes from solid (ice) to liquid
(water) to gas (water vapor).
Phase Changes of Water
120
Energy goes into
evaporation of water.
100
99
98
99
Temperature in Deg. Celsius
87
Energy goes into
heating water from
melting point of zero
degrees Celsius to 64
boiling point of 100
degrees Celsius.
80
60
45
40
20
Energy goes into melting
ice.
12
0
2
0
0
18
3
8
10
13
15
Time in Minutes
18
19
23
25
Water melts at zero degrees Celsius
and boils at 100 degrees Celsius.
Phase Changes of Water
120
Energy goes into
evaporation of water.
100
99
98
99
Temperature in Deg. Celsius
87
Energy goes into
heating water from
melting point of zero
degrees Celsius to 64
boiling point of 100
degrees Celsius.
80
60
45
40
20
Energy goes into melting
ice.
12
0
2
0
0
18
3
8
10
13
15
Time in Minutes
18
19
23
25
The change of state of water
contributes to the Water Cycle, the
unending circulation of water
throughout the planet. See page 13 in
your book for more details.
Humidity
The City of Atlanta, Georgia has
very high humidity in the
summertime! What does it feel like
when it is hot and humid?
What is Specific
Humidity?
Specific Humidity is the
actual amount of water
vapor in the air. It does
not depend on
temperature. It is
expressed in grams of
water per kilograms of air.
What is Relative
Humidity?
Relative Humidity is the
actual amount of water
vapor in the air compared
to the maximum amount
of water vapor the air can
hold.
Relative humidity is
expressed in percentage.
If the air has a specific
humidity of 50 g/kg and
the air will hold 100 g/kg,
what is the relative
humidity?
50 / 100 = 0.5
0.5 X 100 = 50
So the relative humidity is
50%.
If the air has a relative
humidity of 100%, what
will happen?
Clouds or fog will form!
Go here to see the different
types of clouds. Go here to
see even more clouds!
Multiple cloud layers as seen from the
air climbing out of Minneapolis, MN on
12/31/05. Stratus clouds below and
cirrostratus/cirrocumulus clouds above
Clouds or fog will form when
the temperature and dew
point are the same.
But in order for clouds or fog to
form, small dust particles called
condensation nuclei are required!
Fog is a cloud at or near
the ground.
Radiation fog is formed when
moist air near the ground is cooled
to dew point on a cold, clear night.
Advection fog is formed when
warm, moist air moves over a
cold ocean surface. The fog off
of our coast is advection fog.
Cloud Formation
A cloud will form at the elevation
where the temperature and dew point
are the same.
Cloud Stability
Flat clouds like stratus clouds are
stable. This means that the center of
the cloud is colder or at the same
temperature as outside.
Cloud Stability
Clouds with vertical growth
are said to be unstable,
which means the center of
the cloud is warmer than
the air outside. Warm air
will rise.
Cloud Stability
Instability in a cumulonimbus cloud leads to
thunderstorms, lightning, hail, flooding, wind, and
tornadoes.
Lapse rates
A lapse rate is how fast
air cools with altitude.
You can use this value to
calculate the altitude at
which a cloud will form.
Lapse rates
Dry air cools at a rate of
around 10°C per every
1000 meters.
Lapse rates
Moist air cools at an
average of 7°C per every
1000 meters.
Cloud formation
A cloud will form when
the temperature and dew
point temperature are the
same. See an animation
of cloud formation.
Cloud formation problem #1
The temperature at the surface is
20°C and the dew point is 10°C.
Assuming that the dew point
temperature does not decrease
(which it does), what altitude will the
cloud form at? Assume that there is
dry air between the surface and the
cloud.
Cloud formation problem #1
Answer
20° -10° = 10°
Dry air cools 10° C for every 1000
meters.
So, the cloud will form at 1000
meters!
Cloud formation problem #2
The temperature at the surface is
30°C and the dew point is 5°C.
Assuming that the dew point
temperature does not decrease
(which it does), what altitude will the
cloud form at? Assume that there is
dry air between the surface and the
cloud.
Cloud formation problem #2
Answer
30° -5° = 25°
Dry air cools 10° C for every 1000
meters.
So, the cloud will form at 2500
meters!
Precipitation
Precipitation
forms when clouds become
saturated with water.
There are different kinds of
precipitation.
Rain
droplets
grow by
collision
with other
water
droplets.
Drizzle is
a light rain
where the
drops are
small.
Ice
crystals or
super
cooled
droplets
usually
form in
clouds.
If the flake
does not
melt
before
hitting the
ground,
we call
this snow.
Sleet are
raindrops
that refreeze as
they fall
through the
sky.
Freezing rain
is when rain
freezes
instantly
when hitting
the ground.
Hail is frozen
ice that grows
in updrafts and
downdrafts of
thunderstorms.
It finally
becomes too
heavy and falls
to the ground.
Precipitation is
measured using
a rain gauge.
Snow must be
melted to
determine its
water content.
Where does precipitation occur?
Precipitation occurs where moist air
rises and cools.
There is little or no precipitation
where air sinks and warms.
The rain shadow effect determines
precipitation amounts. Go here for
another rain shadow animation.
The rain shadow effect seen from the
air. Picture taken on 12/31/05 on
approach into LAX. Mt. San Jacinto and
Palm Springs are in the distance.
The rain shadow effect as seen from visible and infrared
satellite images taken on May 30, 2007. Notice the
unstable cloud development (cumulonimbus clouds)
over the Sierra Nevada Mountains. Also notice the
stable marine layer (stratus clouds) near the coast.
Infrared Image
Visible Image
Average Precipitation in
California
Dry areas occur on the east (leeward)
side of mountains. Wet areas occur on
the west (windward) side of mountains.
The Northern part of the
state gets more
precipitation because
more low pressure storms
go through that area.
Central and Southern
California are usually
under the influence of
high pressure and clear
weather. See pages 422425 for more details on
pressure patterns.
Water Resources: Owens Valley
The Los Angeles Aqueduct System
Water Resources:
Colorado River
The Los Angeles
Aqueduct System
Water Resources: Groundwater
Water Resources: Local streams
and reservoirs
Population Growth in the Imperial
Valley: Will our water resources be able
to support the projected population
growth?
Red areas mean more and healthier
crops.
June 9,1973
June 30,1992
No more water left over for Mexico?
Compare the crop health in the U.S.
to the crop health just across the
border in Mexico. Can you see the
border?
Go here for a water use survey!
Go here for water science for
schools!