Transcript Mountain Weather - Weather Outreach

The Sun makes our Weather and
Shapes our Climate!
• The sun is really important to
mountain weather because the
heating and cooling of the
Earth makes weather happen!
• To learn more about the sun
click here
http://www.windows.ucar.edu/t
our/link=/earth/Atmosphere/ov
erview.html
– What is our atmosphere made
of? How high does our
atmosphere go? Click here to
learn more.
http://liftoff.msfc.nasa.gov/aca
demy/space/atmosphere.html
•Photo from Solar Voyager:
http://www.solarvoyager.com/images
/art/Earth%20with%20Sun%20by%2
0Claire%20Smith.jpg
Why do we have night and day?
• Which side of the
planet is in daylight
now? (Click here to
find out)
• Where would the
sun be in this
picture? (Click here
to find out)
North Pole
South Pole
Image:
http://pages.towson.edu/mroberge/PG/i
mages/Earth-Sun%20Dec.gif
Why do we have night and day?
• The left side of the picture is
lighter than the right side.
The sun must be shining on
the left side. Once the earth
spins around, the other side
of the earth will be lit. The
side which is lit is in
daylight. The dark side does
not have sunshine lighting it
up so it is night.
North Pole
• The sun is located on the left
side of the picture.
South Pole
Image:
http://pages.towson.edu/mroberge/PG/i
mages/Earth-Sun%20Dec.gif
Areas with More Direct Sunshine
•
•
•
Solar rays, or energy from the sun
(yellow lines) eventually reaches
the earth. The equator (the
redline), receives more sunlight in
a small area. This sunlight heats
the equatorial region.
The solar rays at the top of the
picture which reach North America
are spread out over a larger area.
Since the earth is tilted on an axis,
and the axis relative to the sun
changes during the seasons,
sometimes the northern part of the
hemisphere gets more sunlight in
a small area and sometimes it
gets less.
http://koning.ecsu.ctstateu.edu/plant_
biology/climate.html
Seasons
• Why do we have the
seasons?
– The earth revolves, or
makes one trip around
the sun every year.
Since the earth is tilted
on its axis, during
different parts of the
year, different sections
of the earth get more
direct sunlight.
Northern Hemisphere Seasons
Spring
Winter
Winter
Summer
Fall
Image Modified From:
http://starchild.gsfc.nasa.gov/Images/StarC
hild/solar_system_level2/vivaldi.gif
Sun’s Rays Reach Earth
The sun’s rays heat the ground. Once the ground
is warmed, that energy is moved into the air.
Here are some ways energy is moved from the
earth and through our atmosphere:
Convection:
http://www.ucar.edu/learn/1_1_2_7t.htm
http://www.solarviews.com/eng/edu/convect.htm
Radiation: http://www.ucar.edu/learn/1_1_2_5t.htm
Conduction:
http://www.ucar.edu/learn/1_1_2_6t.htm
What happens to warm air?
• Warm air rises! In the
summer, the sun’s rays
can warm the ground
enough that the air near
the surface will be much
warmer than the
surrounding air.
• To learn more about
rising air, click here:
Website of cool air and
warm air moving with
circulation
http://www.prh.noaa.gov/
hnl/kids/activities.php
Whiteman (2000)
How do Clouds form?
• This warmer air rises
higher up into the
atmosphere until it has
cooled off to the same
temperature as the
surrounding air. If there
is enough moisture in the
air and the temperature
has cooled down enough,
the water vapor in the air
will turn into liquid (cloud
droplets) or solid ice
crystals and will form a
cloud.
Lis Cohen
US Topography
• This is a map of the
topography (elevations)
of the United States. The
highest peaks are white
and the lower valleys are
light green. The
topography of the earth
effects the weather and
climate across the
country.
US Precipitation
• Compare this picture which
shows the average
precipitation across the country
with the US topography
picture. Notice that the highest
values of precipitation are
often found in the mountain
ranges.
• Key
–
–
–
–
–
Red-lowest
Yellow-low
Green-Middle
Blue-High
Purple-Highest
Whiteman (2000), from Water and Climate
Center, Portland, OR.
Storm Track Determines Water
Content of Snow
• Most storms in Utah
are born over the
Pacific Ocean.
– Move with the
subtropical jet stream
or the polar jet stream
– Storms move over the
Sierra Nevada
Mountains and
precipitate out some of
the moisture in the
clouds.
http://www.suite101.com/files/topics/13646
/files/nhjetstreams.gif
Western Mountain Ranges
• This map shows the
mountain ranges in
the west. Storms
often travel from the
Pacific Ocean over
many mountain
ranges before the
storms reach the
Wasatch Range in
Utah.
Whiteman (2000)
Why does the Wasatch get Powdery Snow?
(Before storms reach Utah)
• The Sierra Nevada
Mountains of California
and Nevada and the
Cascade Range of
Oregon and Washington
get most of the
precipitation from the
Pacific storms.
– Because much of the
Pacific precipitation is
intercepted by the Sierras,
the prevailing westerly air
currents are relatively dry
upon reaching Utah.
Lis Cohen
3-D View of the Wasatch
• http://photojournal.jpl.nasa.gov/jpegMod/PIA03
343_modest.jpg
Mountain Precipitation
•
•
•
•
As air is lifted by the mountain, water
vapor can condense into a cloud.
There are a couple of processes that
change these clouds droplets into
much bigger rain droplets.
Precipitation can happen if the rain
droplets get too heavy. These
raindrops then fall to the ground as
rain!
Once the air makes it over the
mountain, it sinks and warms.
Since the air on the other side has less
moisture and the air is sinking, clouds
are not likely to form. This leaves the
back side of the mountains often dry
and desert-like.
Orographic Lift classroom activity:
http://www.pbs.org/edens/denali/orogr
aph.htm#Instructional%20Objectives:
Find source
Sometimes Mountains Create
Warm Winds
•http://www.usatoday.com/weather/wdnslope.htm
Winds and Mountain Range Shape
• The direction of the winds
relative to the shape of
the mountain range will
affect the way that winds
move over the mountains.
The best way to lift the air
is to have the winds move
perpendicular to the
mountain range. From
which direction do the
winds travel in Salt Lake
City (click here to find
out)? How are our
mountains shaped (click
here to find out)?
Whiteman (2000)
Utah’s daily wind cycle
(mountain and valley breezes)
• This is a movie of
how the winds
change through the
day. (Add Wasatch
Winds movie saved
on CD)
• Click here to watch
the wind barbs
change direction
throughout the day:
Mountain Range Shape and
Winds in Utah
• From what direction do
the winds most often blow
in Salt Lake City?
– West/Northwest most of the
time…. Therefore where
would you find wettest and
driest locations?
• Click here to find out
more about Salt Lake’s
climate. Link to climate
slide.
Colors show elevation changes
Why the Wasatch has Powdery Snow
(When Storms Reach the Salt Lake)
• Before storms reach the
Wasatch, they sometimes
move over the Great Salt
Lake. Since the salt lake
is so salty, it never
completely freezes. So in
winter, the Great Salt
Lake can add moisture to
the air which creates
more water droplets and
ice crystals in clouds
which can help create
“lake effect snow.”
Why the Wasatch has Powdery Snow
(Mountains lifting air)
• Once the storms reach the
mountains air is lifted!
– Link here to Mountain
Precipitation Slide.
• The dry air of the Wasatch
makes the snow have more air
and less water in it, so the
snow is fluffy.
– In the Sierra Mountains, one
inch of liquid water can make
10 inches of snow, whereas in
the Wasatch Mountains, one
inch of liquid water can
become 20 inches of snow!
The high Mountains near Salt Lake
City get much more snow than the
Valley Floor
•http://www.usatoday.com/weather/welvsnow.htm
Mountain Warming and Cooling
• Why is it cold on
mountain tops? Do
mountain tops ever get
warmer than air that is
lower down?
http://amos.indiana.edu/li
brary/scripts/coldmt.html
• To listen to the audio
portion click here.
http://amos.indiana.edu/li
brary/coldmt.ram
Lis Cohen
During the Day…..
• During the day, the
sun heats the ground
and the ground heats
the air. This warm
thin layer of air on the
mountain slopes rises
up the mountain side
creating an “Upslope
Flow.”
UPSLOPE
FLOW
WARM
AIR
At Night…..
• At night, the sun no
longer shines on the
mountainside and the
air on the mountain
slopes begins to cool
down. This cool air
slides down the
mountain slope and is
called the “down
slope flow or drainage
flow.”
DOWN SLOPE
FLOW
COOL
AIR
Mountain waves
• How can the
mountains change the
way air flows over
mountains?
– Air can form waves in
the atmosphere and
small spinning circles
of air, called eddies.
Mountain Winds can be dangerous
to Airplanes
• Click on COMET
Mountain Waves
Module
What is there to know about
Mountain Meteorology?
• There are still things
to be learned about
mountain waves so
researchers are still
engaging in projects
and experiments to
better understand
mountain waves.
Picture: Sierra Waves project 1950s
Mountain Wave Indicators
• Lenticular clouds can
develop when air moves
quickly over the top of
mountains. Standing
waves, like water flowing
over a rock in rapids, can
develop which can be
dangerous for airplanes.
Click here to learn more
http://meted.ucar.edu/me
soprim/mtnwave/print.htm
NCAR/UCAR/NSF
Mountains Channeling Winds
• Sometimes mountains
channel the winds so they
move very quickly
through a small space.
This movement is similar
to how water moves
quickly out the spout of a
hose if you put your finger
over part of the spout.
Whiteman (2000)
Winds Shaping Snow
• Winds can move snow
from one side of the slope
to another and can build
giant cornices as shown
in the figure. These
cornices can be very
dangerous to walk on.
Figure a shows where
this cornice might break.
If these cornices break,
you can trigger an
avalanche.
Whiteman (2000)
Winds and Plants
• Strong winds can affect
the trees and plants.
Look for signs of winds
along the mountains and
in the valley. Which way
do you think the winds
might be blowing?
• In addition to wind, water,
sunlight and plant species
can affect tree growth.
Whiteman (2000)
Can air be warmer at the top of a
mountain?
• Sometimes storms with
cold air move up to a
mountain and the cold air
does not make it all the
way across. The cold air,
since it is more dense,
can easily remain in what
is called a cold pool (click
here to link to Jenny’s
stuff).
Whiteman (2000)
Mountain Climates
• To learn more about
climates and biology
click here (for older
students)
http://instruct.uwo.ca/
biology/320y/climveg.
html
http://www.emc.maricopa.e
du/faculty/farabee/BIOBK/Bi
oBookcommecosys.html
Mountain Climates and Plants
http://curriculum.calstatela.edu/courses/builders/lessons/less/les3/lat-alt.html
Mountain Climates and Plants
http://mail.aquinas.org/~atlas/physgeog/biomes/Websit
es/mid%20latitude%20broadleaf%20forest/climateimg1
Activities related to mountains and
climate
http://www.cstone.net/~bcp/4/4NGeo.htm
http://school.discovery.com/lessonplans/prog
rams/mtbarrier/
Utah Climate Info
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
Name ___________________________________________________
1. What is Utah's highest temperature?
http://www.usatoday.com/weather/wheat7.htm
2. What is Utah's coldest temperature?
http://www.usatoday.com/weather/wcstates.htm
3. What is the average temperature in Salt Lake City for July?
http://www.cityrating.com/cityweather.asp?city=Salt+Lake+City
4. What is the average temperature in your city for January?
http://www.cityrating.com/cityweather.asp?city=Salt+Lake+City
5. What is the 5 day forecast along the Wasatch Front?
http://www.met.utah.edu/cgi-bin/jimsteen/campus_forecast3.cgi
6. What is today's forecast for Salt Lake City?
http://www.wrh.noaa.gov/slc/forecast/textproduct.php?pil=ZFP
7. What types of severe weather are found in Utah?
8. Write some facts about lightning or tornadoes.
http://www.wildweather.com
9. Where is it the coldest today?
Map - http://www.usatoday.com/weather/temppic/wtempusa.htm
Places - http://www.usatoday.com/weather/wext.htm
10. Where is it the hottest today?
Map - http://www.usatoday.com/weather/temppic/wtempusa.htm
Places - http://www.usatoday.com/weather/wext.htm
Other climate data:
http://www.wrcc.dri.edu/cgi-bin/clilcd.pl?ut24127
Finding out about Utah’s Weather
• Wild Weather
– http://www.usatoday.com/weather/wheat7.htm
• Five Day Forecast
– http://www.wrh.noaa.gov/saltlake/
– http://www.wildweather.com
– http://cirrus.sprl.umich.edu/wxnet
Glossary
•
Precipitation- rain, hail, sleet or snow.
http://amsglossary.allenpress.com/
glossary/search?p=1&query=preci
pitation&submit=Search
•
Topography- characteristics
•
Orographic- average height of the land
of land in terms of
elevation, slope, and orientation
http://amsglossary.allenpress.com/
glossary/search?p=1&query=orogr
aphic&submit=Search
•
•
•
•
•
•
Orographic lift- air lifted as it travels over mountains
Perpendicular- at a 90 degree angle (see diagram)
Axis- an imaginary line that an object rotates (or spins) around
mountain ranges- a group of mountains
Water vapor- water as a gas (this gas is invisible)
Condenses- the phase change of a gas turning into a liquid
•
Subtropical jet stream-subtropical jet stream—A
band of relatively strong winds concentrated
between 20° and 40° latitude in the middle and
upper troposphere. It can be present at any
longitude but is generally strongest off the Asian
coast. See jet stream. (AMS Glossary 2000)
•
jet stream—Relatively strong winds concentrated
within a narrow stream in the atmosphere.
http://amsglossary.allenpress.com/glossary/search?id=j
et-stream1
References
• Whiteman, C. D., 2000: Mountain
Meteorology: Fundamentals and
Applications. Oxford University Press,
New York, 355pp.