Download 01-29-09 Weather Map

NREM 407/507
January 29, 2009
Day 6
• Work on Weather Lab Together
• Power Points Are Due Next Friday, Feb 6
@ Midnight (e-mailed)
• Lab next Tuesday OUTDOORS – all period
watch e-mail for any changes
Furtwangler Glacier – Mt. Kilimanjaro
Mt Kilimajaro
Tanzania
19,340 ft above sea level
Tallest free standing
mountain – rises 15,000ft
1990
Mt Kilimanjaro
Climate Change
Impacts on Glaciers
Sources of Stream flow
2000
Boulder Glacier , Mount Baker
Cascades Mtns, Washington
Stream flow generated by Glacier
Retreated 1,500 ft in 8 years
Terminus of Glacier
A 5 mi2 watershed receives 2 in of rainfall. 10% of that produces channel
storm flow that discharges in 10 hours. What is the average cfs of the
storm flow? 1 mi2 = 640 ac; 1 ac = 43,560 ft2
5 mi2 x 640 ac = 3,200 ac
2”/12” = 1/6 ft = 0.167 ft x 3,200 ac = 533 ac-ft x 43,560 ft2 =
23,232,000 ft3 x 10% = 2,323,200 ft3 of storm flow in 10 hours
2,323,200 ft3/(60 sec/min x 60 min/hr x 10 hr = 36,000 sec) = 64.5 cfs
Weather &Topography Give Rise to Climate, Biomes, Rivers,
Runoff
Coastal
Conifer
Forest
Intermountain
Mid Grass
Region
Prairie
Intermoutain
Grassland
Tall Grass
Prairie
Great
Basin
Central Valley
Short
Grass
Prairie
Eastern
Deciduous
Forest
Southern
Conifers
Precipitation
Streamflow
Water Is Awesome
All three states at
normal earth
temperatures
Solid Water
Hail
Liquid Water
Water
Vapor
Water Droplets
How Do Clouds Form?
Convectional
lifting
• Warm moist air rises & cools
• Cooler air holds less vapor
• Air becomes saturated
• Condensation occurs
around condensation nuclei
Frontal lifting
Orographic
lifting
Condensation level
Kinds of Precipitation
• Rain – liquid drops starting as liquid or snow
falling through warm air
• Freezing rain – snow melts, hits cold air, freezes
when it hits a cold surface
• Sleet – snow melts in warm air, refreezes falling
through colder air.
• Snow - falling through cold air never melting
Clouds In Contact With the Ground
Radiation Fog
Warm moist air cooled from below by contact with a cooling earth
surface – cooling by longwave radiation, local, shallow, disappears right
after sunrise.
Advection Fog
Forms when a warm air mass flows over a cold surface and cools to
saturation from below, wide-spread & can last through morning or day.
Ice Fog
Ice forms without condensation nuclei in supercooled air – air temp has
to be at least -15 F – widespread.
Hoar Frost
Ice crystals form on small frozen surfaces like branches or barbed wire.
Radiation Fog
Advection Fog
Energy Exchange with
Changes of State
Sensible vs Latent Heat
Heating 1 gram of water 0 – 100 C = 100 cal
Evaporating 1 gram requires 540 cal of energy
Condensing 1 gram of vapor releases 540 cal
Freezing 1 gram releases 80 cal, thawing requires 80 cal
Group Exercise
Why are large bodies of water cooler in summer & warmer
in winter?
Role of Water and Heat Transfer
Air Circulation – Convection Cell
Advection - wind
Subsidence
Convection
Advection - wind
Large lake
cool
Land - warm
Sunny Calm Morning – Summer Conditions
On-shore breezes
Air Circulation – Convection Cell
Subsidence
Advection - wind
Convection
Advection - wind
Large lake
warm
Land - cool
Clear Calm Night – Sky Wide Open – Surface Cools
Off-shore breezes
20,000 ft
- 42.5 F
10,000 ft
-12.5 F
Cloud
5,000 ft
- 80 F
Group Activity
What happens if 30 F air is
lifted to 10,000 ft & 20,000 ft?
-25 F
Dry adiabatic lapse
rate = 5.5o/1,000 ft
Cools @
3.0F/1,000ft
Moist adiabatic lapse
rate = 3.0o/1,000 ft
2.5 F
Condensation level
Cools @ 5.5F/1,000 ft
Air expands less dense
30 F
Sea level
Moist Air rises &
condensation begins at
5,000 ft
Cools @ 5.5F/1,000 ft
30 F
Dry Air
No condensation
all the way up
Convectional
lifting
Group Activity
What are the temperatures
at 4,000 ft - Condensation
Level, 15,000 ft and sea level
on the other side?
Frontal lifting
5F
15,000 ft
Rain – lost
moisture
Orographic
lifting
Drops
@ dry
adiabatic
lapse
rate
38 F
Condensation
Level – 4,000 ft
60 F
87.5 F
Climate & Weather
What Kinds of Energy are Important to Watersheds:
1.
2.
3.
4.
Radiant
Thermal or heat (sensible & latent)
Mechanical (kinetic & potential)
Chemical
Movement of radiant/heat energy:
1. Radiation
2. Conduction
3. Convection
4. Latent Heat
Radiation – The Energy Source
R = Constant * T4
Higher temperatures
shorter wavelengths
energy (ultraviolet vs infrared)
When radiation hits a surface it can be:
a + r + t = 1 (absorbed, reflected, transmitted)
In the atmosphere it can also be scattered
s + a + r + t = 1 (scattered – gives blue sky)
Radiation from atmosphere
Solar Radiation – Shortwave (high energy)
Earth (Terrestrial) Radiation – Longwave (low energy)
more
Group Exercise
Albedo – reflection – reduces heat load on the surface
Which one of each set below reflects more radiation:
Fresh snow vs old snow
Dark soil vs light colored soil
Wet soil vs dry soil
Forest vs Grassland
Hardwood (deciduous forest) vs conifer forest
Lake surface when the sun is near the horizon vs nearly
overhead
More
Slope & Radiation
Perpendicular radiation –
most energy per unit surface area
Higher Potential
Evapotranspiration
Group Activity
Cooler – Moister
Supports more plants
S/W facing
N/E facing
What are the aspects in this valley and why?
Describe valley wind movement during the day & night and why?
Earth’s Tilt in relation to Sun Important in Seasonal Heating
Ames
Ames
Ames
Ames
Angle of Direct Shortwave Radiation at Solar Noon – Importance of Aspect
Result
Differential
Heating of
The Earth’s
Surface
90 – (23.5+23.5) = 43
90 – 23.5 = 66.5
23.5
23.5
23.5
47
66.5
Impacts
Lifting &
Subsiding
Air &
Associated
Moisture
90 – (66.5-23.5) = 47
90 – (90-23.5) = 23.5
Winter Solstice – December 21
Calculate the angles in the Northern Hemisphere at the Solar Equinoxes
Arctic
66.5
Ames - 42
Cancer – 23.5
90 – 90 = 0
90 – 66.5 = 23.5
90 – 42 = 48
90 – 23.5 = 66.5
Equator
23.5
90
Capricorn – 23.5
Antarctic
66.5
Solar Interception at the Equinoxes (March 21, Sept 21)
Group Activity
What south-facing slope in Ames gets perpendicular radiation
at the equinoxes (48o)?
South-facing
Solar altitude
North-facing
90
42
48
180
What north-facing slope gets no direct shortwave radiation?
Atmospheric
Circulation –
Big Convection
Cell
Ames
42 N
Cools as it moves
North – Drops
Very Dry
Warmest at
Equator - Lifting
Where is the Major Global Precipitation?
Frontal
30 N
Convectional
Equator
30 S
Frontal
Where are the World’s Major Deserts?
30 N
Great Basin
Mojave
Sonoran
Iranian/Thar
Saharan Arabian
Gobi
Equator
Atacama
30 S
Namibian
Patagonian
Australian
Kalahari
Subsiding – Warm/Dry Air (Subsidence)
Major Air Mass Source Regions for North America
Cold/dry
cP/cA
Cool/Moist
mP
Warm/Moist
mT
c – Continental (dry)
m – Maritime (wet)
P = Polar (cold); A = Arctic
T = Tropical (Warm)
Equator
Paths of Movement of Major North American Air Masses
cP/cA
mP
mT
Equator
Air Masses Consist of Dense
Subsiding (dropping) Air
H
L
Air circulation
Clockwise & out
Air circulation
Counterclockwise & in
Air circulation
Clockwise & out
When 2 Air Masses Meet They
Create A Trough of Low Pressure
Between Them (less dense rising air)
Location of Fronts & Low Pressure Cells
H
Surface 600 mph
Air Still 800 mph
800 mph
(air/surface)
1,000 mph
(air/surface)
Earth is not a perfect
sphere
Velocity of surface at
the equator ~ 1,000 mph
to the east.
At Ames ~ 750 mph to
the east.
Result is deflection to
the right of air moving in
N hemisphere
Coriolis Force
Circulation Around
H and L Pressure Cells
Diverge from the
center
subsiding air
Converge at the
center and lift
Pressure Gradient
Coriolis Force
Actual Wind
H = subsiding or sinking air
L = convectional lifting
Cold Center – Dense Air - Sinks
Warm Center – Lighter Air - Rises
Pressure Gradient from H to L
from inside to outside
Pressure Gradient from H to L
from outside to inside
Flow turns to right & clockwise
Flow turns right & counterclockwise
H = subsiding or sinking air
L = convectional lifting
What are the wind directions at the following locations:
X
CALM
X
X
X
X CALM
X
X
Chicago
Las Vegas
New Orleans
Detroit
New York
Seattle
Shreveport, LA
What is Going On Where the Air Masses Meet – Fronts?
cP/cA
Occluded Front
Warm Front
Stationary Front
mP
Cold Front
mT
Oriented NE to SW
Cold Front
NE
Slope of Frontal Surface = 1:50
to 1:150 (1 mile vertical for each
mile horizontal)
Move at 10-40 mph
SW
Wind shift with
passage SW to NW
Wind
Speed
in
Cold
Air
Clouds – cumulus (vertical)
Rain – short, intense
right at front
Warm Air
Warm Front
Oriented NW to SE
Slope of Frontal Surface =
1:100 to 1:300
Move at 5-20 mph
NW
Wind shift with passage ENE to SW
SE
Clouds –
stratus
Rain – long,
gentle ahead
of front
Cumulus – vertical General Types of Clouds
Stratus - layer
Alto – mid level
Cirro – high level
5-20 mph
10-40 mph
Occluded Front
Development of
Occluded Front
Faster moving cold
front catches up to
warm front lifting
warm air off the
ground
Once warm air loses
contact with ground it
loses source of moisture
& dies
Occluded Front
Please Take Out Your Lab
Turn to Page 9 – Synoptic Weather Map Exercise
Synoptic
Weather Map
6 pm Yesterday
Radar – 1-28 5 pm
World 1-28-09 6pm
L
H
H
H
H
L
L
H
Synoptic
Weather Map
6 pm Yesterday
H
H
Pressure
In Millibars
Station Report – Page 15
Synoptic Map
The center of air masses are H
pressure cells.
Where 2 air masses meet a
frontal surface develops.
Air from a cold air mass
moving into a warm air mass
creates a cold front.
Air from a warm air mass
moving up and over a cold air
mass creates a warm front.
When neither air mass is moving
a stationary front is created.
Low pressure disturbances
form along fronts.
Synoptic Weather Map
Isobars – lines of equal
pressure –
Plotted at 4 mb intervals.
1,000 mb = 1 bar ~ 15 lbs/in2
1,013 –1,040 ~ High pressure
980 – 1,012 ~ Low pressure
Station Model Data – major
NOAA NWS recording
stations are plotted on
map.
Model provides extensive
data – page 15 Weather
Map Exercise
Pages 15-21 Weather Map
P 21
P 21
P 19
Pages19 & 21 Weather Map Exc.
Can Use This Map To Predict What Is Going To Happen
Synoptic Map
The center of air masses are H
pressure cells.
Where 2 air masses meet a
frontal surface develops.
Air from a cold air mass
moving into a warm air mass
creates a cold front.
Air from a warm air mass
moving up and over a cold air
mass creates a warm front.
When neither air mass is moving
a stationary front is created.
Low pressure disturbances
form along fronts.
24 Hours Later
Warm
Sector
Figure 1 – Wave Cyclone With Station Data – Last Page of Exercise
Page 10 – a (1) Draw Isobars – Plotting those evenly divisible by 4 mb – Begin
with 1004 around L on Wave Cyclone
a (2) Label L’s & H’s
a (3) Label fronts
Draw Isobars – Plotting those evenly divisible by 4 mb – Begin with 1004 around
L on Wave Cyclone
1020
H
1024
H
1028
1024
1020
1008
1016
1012
Questions a 1-3
L
1004
H
cP
H
H
L
H
1008
L
1004
mT
Questions a 4 & 5
H
Calm &
Dew Point =
Actual Temp
H
Fractostratus
Of Bad Weather
1008
H
L
1004
Wind
off
warmer
water
Cumulonimbus
with anvil shaped top
Questions b 1-4
H
cP
Falling
Steady then falling
H
Steady
H
L
Rising
1008
L
1004
mT
Question b 5
H
H
~170o
H
L
H
~60o
L
1004
500/24 = 21 mph
Question c 1-2
400/24 = 17 mph
H
275/12 = 23 mph
125/12 = 10.5 mph
Counterclockwise
Backing
Veering
Clockwise
Veering
Clockwise
12 hrs
Questions c 3-6
New Orelans
7 pm
H
H
L
Warm
Sector
275/20 mph for L=
13.75 hrs
8:45 pm
Questions c 8-12
100/10 mph for warm front
H=
10 hrs = 5 pm Feb 15