Download Hydrologic Cycle

23-1
Hydrologic Cycle
Surface-Atmosphere Exchange of Water
Water Cycle
Science Concepts
Evaporation
Condensation
Precipitation
Runoff
Climate and Global Change Notes
23-2
Hydrologic Cycle
Change in Annual Precipitation
Climate and Global Change Notes
23-3
Hydrologic Cycle
Modeled Environmental Water Scarcity Index
•
•
•
Scarcity is where the amount of water removed from the system puts the
ecosystem at risk by tapping into the environmental water demand, i.e., the
amount of water needed to sustain the integrity of the ecosystem
Areas above 0.4 are under ecosystem environmental stress
Areas higher than 0.8 (orange and red) are highly-stressed environmentally
http://www.iucn.org/themes/wani/eatlas/html/gm16.html
Climate and Global Change Notes
23-4
Hydrologic Cycle
The Water Cycle
•
All streams
flow into the
sea, yet the
sea is never
full.
To the place
the streams
come from,
there they
return again.
Ecclesiastes
1:7 (New
International
Version)
http://ga.water.usgs.gov/edu/watercycle.html
Climate and Global Change Notes
23-5
Hydrologic Cycle
The
Water
Cycle
1012 m3 per year
Climate and Global Change Notes
23-6
Hydrologic Cycle
GOES Water
Vapor Image
Climate and Global Change Notes
23-7
Hydrologic Cycle
GOES Visible
Image
Climate and Global Change Notes
23-8
Hydrologic Cycle
Mean Global Precipitable Water (cm)
•
Annual Average
http://isccp.giss.nasa.gov/cgi-bin/browsed2
Climate and Global Change Notes
23-9
Hydrologic Cycle
Mean Global
Precipitable Water (cm)
(Con’t)
•
Seasonal variability
S.W. Seemann, J. Li, W.P. Menzel – Univ. Wisconsin, NOAA
Climate and Global Change Notes
23-10
Hydrologic Cycle
Amazon Seasonal Variability
•
Note seasonal rainfall variability
•
Amazon and Tropical seasons revolve
around wet/dry not hot/cold
http://earthobservatory.nasa.gov/
Study/AmazonLAI/
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Climate and Global Change Notes
23-11
Hydrologic Cycle
90
Honolulu WSO Airport
Ave Max Temp (°F)
Ave Min Temp (°F)
85
Ave. Max. Temp. = 84.0°F
80
QuickTime™ and a
TIFF (Uncom pressed ) decomp ressor
are n eeded to see thi s picture .
75
•
21° 20’ N, 157° 55’ W
•
Elevation = 10 ft
•
Averages for
10/1/49-3/31/05
70
65
Ave Max Temp (°F)
Ave Min Temp (°F)
Ave. Min. Temp. = 70.2°F
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
80
65.7
80.1
65.8
81
67.2
82.4
68.8
84.2
70.4
86.1
72.4
87.1
73.6
88
74.4
88
73.7
86.4
72.5
83.7
70.5
81
67.6
4
Ave. Annual
Precipitation = 20.75 in
3
2
1
0
http://www.wrcc.dri.edu/cgi-bin/
cliMAIN.pl?hihono
Ave Precip (in)
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
3.37
2.43
2.59
1.21
0.94
0.38
0.54
0.62
0.66
1.9
2.8
3.3
Climate and Global Change Notes
23-12
Hydrologic Cycle
Mean January Moisture
Dewpoint Temperature (°F)
1961-1990
Relative Humidity (%)
1961-1990
http://www.nndc.noaa.gov/
cgi-bin/climaps/climaps.pl
Climate and Global Change Notes
23-13
Hydrologic Cycle
Mean July Moisture
Dewpoint Temperature (°F)
1961-1990
Relative Humidity (%)
1961-1990
http://www.nndc.noaa.gov/
cgi-bin/climaps/climaps.pl
Climate and Global Change Notes
23-14
Hydrologic Cycle
Average Dewpoint Temperature (°F) (1960-1990)
January
July
Annual
http://www.nndc.noaa.gov/
cgi-bin/climaps/climaps.pl
Climate and Global Change Notes
23-15
Hydrologic Cycle
July Dewpoint Temperature & Diurnal Temperature Range
(°F)
Dewpoint Temperature
Diurnal Temperature
Range
http://www.nndc.noaa.gov/
cgi-bin/climaps/climaps.pl
Climate and Global Change Notes
23-16
Hydrologic Cycle
Average Relative Humidity (1960-1990)
January
July
Annual
http://www.nndc.noaa.gov/
cgi-bin/climaps/climaps.pl
Climate and Global Change Notes
23-17
Hydrologic Cycle
http://www.meted.ucar.edu/
Average Annual Precipitation (1961-1990)broadcastmet/watershed/media/
graphics/unit_6/nat_atlas_precip.jpg
•
Annual
Climate and Global Change Notes
23-18
Hydrologic Cycle
Surface-Atmosphere Exchange of Water (Con’t) Science Concepts
Saturation Processes
Increase Vapor
Cooling
Lifting
Mixing
Radiational Cooling
Dry Adiabatic & Moist Adiabatic
Process
Condensation Types
Dew/Frost
Fog
Haze
Cloud Droplets
Climate and Global Change Notes
23-19
Clouds and Precipitation
Atmospheric Saturation Processes
•
Add moisture - Infrequent (Steam Fog)
•
Cool to dewpoint temperature - Usual process
-
Lifting
-
Mixing
-
Radiation
Climate and Global Change Notes
23-20
Clouds and Precipitation
Cloud Formation
•
Condensation process
-
Condensation nuclei
>
What are they?
‡
‡
‡
>
I am not sure how clouds
get formed. But the clouds
know how to do it, and that
is the important thing.
Sea salt
Combustion products - smoke
Dust - Clay from plowed fields
What is their distribution?
‡
‡
‡
-
Science quotes of 5th and
6th graders -
Decrease with height - For Example: 0.1 as many at 3,000 ft as
at surface; 0.01 as many at 14,000 ft as at surface
More over cities than country
More over land than ocean - More giant nuclei over oceans
Hygroscopic nuclei - Begin to attract water vapor at RHs as low as 70%
>
What are they?
‡
Sea salt - Most common
Climate and Global Change Notes
23-21
Clouds and Precipitation
Types of Condensate
•
Science quotes of
5th and 6th
graders -
Dew
-
Caused by radiational cooling of a surface to the
dewpoint temperature of
the air
-
Typical conditions
>
>
>
-
Dew is formed on
leaves when the
sun shines down
on them and
makes them
perspire.
Clear skies
Calm winds (little mixing)
Nighttime
Dewpoint temperature above 32°F
Climate and Global Change Notes
23-22
Clouds and Precipitation
Types of Condensate (Con’t)
•
Frost
-
Caused by radiational cooling of a surface to the dewpoint temperature of
the air
-
Typical conditions
>
>
>
-
Clear skies
Calm winds (little mixing)
Nighttime
Dewpoint temperature below 32°F
Quote
“Teg weather report on the car radio had predicted a low of 35 degrees, and Pittmen
believed it, seeing frost come out of his mouth.”
David Morrell, "Desperate Measures" (p. 295)
What is wrong with this statement?
Climate and Global Change Notes
23-23
Clouds and Precipitation
Types of Condensate (Con’t)
•
Fog
-
Defined as a cloud on the ground
-
Caused by
>
Cooling of the air to its
dewpoint temperature
‡
‡
>
Most common cause
Types of “cooling fog”
◊
Radiation fog
◊
Advection fog
◊
Upslope fog
In order to save the army during the
Revolutionary War Washington retreated from
Long Island overnight on Aug. 29, 1776. By
sunrise on the 30th not all the troops had
been ferried across the river to the NY side.
However, a heavy fog had settled over the
river so they could continue to cross without
being observed by the British troops and war
ships. Within an hour after the boats had
carried the last of the 9,000 troops safely
across, the wind shifted and the fog
dispersed. Fog had helped save the army.
1776, David McCullough, pp. 186-191
Evaporation of enough water to saturate the atmosphere
‡
‡
Least frequent cause
Types of “evaporation fog”
◊
Steam fog
◊
Warm-rain fog
-
Dissipation (“burns-off”) by solar heating the surrounding ground; causes
mixing at edges
-
Annual average days with fog
Climate and Global Change Notes
23-24
Clouds and Precipitation
Radiation and
Valley Fog
Alabama
Rivers
Note contrails
Bright yellow is fog
Valley fog
AVHRR Satellite - 4 November 1999
- Color enhanced (Visible,
near infrared (~1 micron),
infrared (~3.7 micron)
Climate and Global Change Notes
23-25
Clouds and Precipitation
Types of Condensate (Con’t)
•
•
Haze
-
Caused by particles (“large”) that scatter all wavelengths of light equally
-
Increases as RH becomes greater than 70% because of hygroscopic nuclei
Cloud droplets
-
Cooling of the air aloft to its dewpoint temperature
Climate and Global Change Notes
23-26
Hydrologic Cycle
Surface-Atmosphere Exchange of Water (Con’t) Science Concepts
Precipitation Physics (Con’t)
Cloud Growth Processes
Surface Tension
Solute Effect
Curvature Effect
Droplet Multiplication
Cascade Effect
Climate and Global Change Notes
23-27
Clouds and Precipitation
Science quotes
of 5th and 6th
graders -
Cloud Droplet Growth Processes
•
•
Solute effect - Solution of water and nuclei material
-
Helps droplet grow
-
Decreases as droplet becomes larger
-
Larger condensation nuclei, larger this effect. Thus,
larger nuclei grow larger droplets
Curvature effect - Caused by surface tension around droplet
-
Hinders droplet grow
-
Decreases as droplet becomes larger
To most people
solutions mean
finding the
answers. But to
chemists
solutions are
things that are
still all mixed up.
Cloud Droplet Multiplication Process
•
Cascade effect - Large drops break into several smaller drops
Climate and Global Change Notes
23-28
Hydrologic Cycle
Surface-Atmosphere Exchange of Water (Con’t) Science Concepts
Precipitation Physics (Con’t)
Rain Drop Formation
Collision and Coalescence Process
Bergeron Process
Terminal Velocity
Gravitational Force
Drag Force
Pressure Gradient Force
Supercooled Water
Saturation Over Water Ice
Precipitation Types
Climate and Global Change Notes
23-29
Clouds and Precipitation
Forces on a Falling Object
•
Terminal velocity ~120 mph
http://cyberbuzz.gatech.edu/skydive/photos/othermisc/
http://www.fcsurplus.ca/army/300745b.gif
Climate and Global Change Notes
23-30
Clouds and Precipitation
Forces on a Cloud or Rain Drop
•
Drag Force => Depends on square of Velocity and Shape of Drop
•
Pressure Gradient Force => Depends on Volume of Drop
•
Gravitational Force => Depends on the Mass of the Drop
D = Cd r A V2 / 2
D = Drag force
Cd =Drag coefficient
(usually determined
experimentally)
r = Density of fluid (air)
A = Reference area
(includes shape, etc.)
V = Velocity
Drag
Force
Pressure
Gradient
Force
Cloud
or
Rain Drop
Gravitational
Force
Climate and Global Change Notes
23-31
Clouds and Precipitation
Atmospheric Particles
Name
Large Ions
Smoke and Dust
Large Condensation Nuclei
Giant Condensation Nuclei
Cloud Droplets
Rain Drops
Diameter (cm)
10-6 to 10-5
10-5 to 10-4
10-5 to 10-4
10-4 to 10-2
10-4 to 10-2
10-2 to 1
# per cm3
103 to 104
variable
102
1
Climate and Global Change Notes
23-32
Clouds and Precipitation
Particle Terminal Velocities
Particle Type
Condensation Nuclei
Diameter (cm)
2 X 10-5
m/s
1 X 10-7
mph
2 X 10-7
Small Cloud Droplets
1 X 10-5
3 X 10-3
Typical Cloud Droplets
2 X 10-3
1 X 10-2
2 X 10-2
Large Cloud Droplets
10-2
0.27
0.18
Small Rain Drops
0.1
4.0
8.9
Typical Rain Drops
0.2
6.5
14.6
Large Rain Drops
0.5
9.0
20.1
Climate and Global Change Notes
23-33
Clouds and Precipitation
Did you know -
Raindrop Growth Process
•
Raindrop 100 times larger diameter than cloud drop;
1,000,000 time larger volume
•
How does this tremendous growth occur?
-
Coalescence process - “Warm” clouds
>
Terminal velocity
‡
‡
‡
Gravitational force
Pressure gradient force
Drag force
>
Large drops fall faster than smaller drops
>
Large drops collect smaller drops
Houses used to have
thatched roofs - thick
straw, piled high, with no
wood underneath.
Because it was the a
place animals could get
warm, cats and other
small animals (mice,
bugs) lived in the roof.
When it rained, the thatch
became slippery and
sometimes the animals
would slip off the roof.
Hence, the saying "It's
raining cats and dogs."
Climate and Global Change Notes
23-34
Clouds and Precipitation
Raindrop Growth Process (Con’t)
•
Raindrop 100 times larger diameter than cloud drop; 1,000,000 time larger
volume (Con’t)
•
How does this tremendous growth occur? (Con’t)
-
Bergeron-Findeisen or ice process - “Cold” clouds
>
Freezing nuclei
‡
‡
Not enough in the atmosphere
“Pure” water may not turn to ice until -40°C
>
Between 0°C and -40°C, cloud is mixture of ice and liquid. At
temperatures below (i.e., heights above) -40°C, cloud is all ice.
>
Ice crystals grow at expense of liquid drops
Climate and Global Change Notes
23-35
Clouds and Precipitation
Comparison of Maritime and Continental Rain Clouds
Maritime
Continental
Number of Nuclei
940 cm-3
9500 cm-3
Droplet Concentration
50 cm-3
200 cm-3
17 x 10-6 m
11 x 10-6 m
Median Droplet Diameter
Climate and Global Change Notes
23-36
Clouds and Precipitation
Precipitation Classification
•
Drizzle
-
•
Intermittent or Continuous Precipitation
-
•
Small, numerous drops falling out of fog or low layer stratus clouds
Indicative of stable stratification with little vertical motion
Rain or snow
Falling more or less evenly from altostratus or nimbostratus clouds
Caused by widespread and slow upward movement of large masses of air
Showers (Squalls, Flurries)
-
Precipitation with short duration with fair intervals
Caused by cumulus or cumulonimbus clouds, i.e, convection
Indicative of unstable stratification with fairly strong upward vertical
motion in localized regions
Climate and Global Change Notes
23-37
Clouds and Precipitation
Types of Precipitation
•
Virgae
-
•
Rain that evaporates below cloud
base, but before reaching the ground
Rain
-
Lower atmosphere above freezing
Drops large enough to fall relative to
air motions
http://www.ucar.edu/imagelibrary/1600-1650.html
http://www.wrh.noaa.gov/spokane/
042700/tstms.htm
Climate and Global Change Notes
23-38
Clouds and Precipitation
Types of Precipitation
•
Freezing Rain
-
Ground at 0°C or colder
Very shallow layer of air near the ground
at near 0°C or colder
Layer of air above this shallow layer at
temperatures above 0°C
QuickTime™ and a
TIFF (Uncom presse d) decom presso r
are n eeded to see th is picture.
http://ww2010.atmos.uiuc.edu/
(Gh)/guides/mtr/cld/prcp/zr/frz.rxml
http://www.srh.noaa.gov/lzk/html/win121300.htm
Climate and Global Change Notes
23-39
Clouds and Precipitation
Types of Precipitation
•
Sleet, Grauple, Ice Pellets
-
Clear ice “drops”
Precipitation is in the form of liquid
drops at sometime as it falls
Deeper layer of air above the ground
at 0°C or colder
Layer of air above this deeper layer at
temperatures above 0°C
QuickTime™ and a
TIFF (Uncom pressed) decomp ressor
are n eeded to see this picture.
http://ww2010.atmos.uiuc.edu/
(Gh)/guides/mtr/cld/prcp/slt.rxml
Climate and Global Change Notes
23-40
Clouds and Precipitation
Types of Precipitation (Con’t)
•
Science quotes of 5th and 6th graders -
A blizzard is when it snows sideways.
Snow
Opaque ice crystals or flakes
Crystals form at temperatures below 0°C
by the process of deposition
QuickTime™ and a
TIFF (Uncom presse d) deco mpress or
No liquid phase
are n eeded to see this pictu re.
Ground at or near 0°C or colder
Layer of air above the ground at
temperatures below 0°C
http://ww2010.atmos.uiuc.edu/
(Gh)/guides/mtr/cld/prcp/snow.rxml
http://www.noaanews.noaa.gov/stories/s592b.htm
http://www.ucar.edu/imagelibrary/
1100-1133.html
Climate and Global Change Notes
23-41
Clouds and Precipitation
Types of Precipitation (Con’t)
•
Hail
-
-
Large balls or lumps of ice
Often formed of concentric
rings of clear
and opaque ice
Formed in clouds with strong
updrafts, i.e., convective
clouds
http://www.eas.slu.edu/Photos/
hail.html
Record Hail Stone - 7” diameter,
18.75’’ circumference fell in
Aurora, NE, 22 June 2003
http://www.ucar.edu/imagelibrary/1
134-1166.html
Climate and Global Change Notes