Download Storms - Dr. Augustine Science

Weather and Storms
Bell Work
1. What makes the prevailing winds in the
Ferrel Cell unique compared to those in
the Polar and Hadley Cells?
2. Carrboro, NC is at ~35°N latitude.
a) What is the prevailing winds and wind
direction here?
b) Within what pressure cell do we lie
and are we near a low or a high
pressure region?
1. Meteorology - the study of
atmospheric phenomena
2. Weather - the condition of
the atmosphere at a certain
time & place
3. Climate - Long term weather for an
area averaged over many years.
Weather Instruments
Barometer• measures air pressure:
rise of mercury in a tube ↑
as pressure on mercury in
a bath ↑.
Thermometermeasures temperature by using a liquid
that expands or shrinks as it is heated or
cooled, moving up or down in a tube.
Windsockmeasures wind direction
Anemometermeasures wind speed: wind pushes on
cups causing them to spin and a dial
attached to generator shows speed of
wind.
Station Model: A symbolic summary of the
weather data for a location
Isobars- lines that connect points
of equal pressure
Bell Work
Look at the station
model shown:
1. What is the temperature (in F)?
2. What is the dew point temperature?
3. What is the wind speed and
direction?
4. Are there any clouds in the sky?
Bell Work
• Begin work on the FORECASTING
THE WEATHER worksheet.
• Notebook quiz at 3:05
Bell Work
Get an Earth Science textbook & read pages 561–563
(Weather in North America)
Answer the following in your notebook:
1. What is the source & type of air mass that is
responsible for lake effect snowstorms in
Rochester?
2. What is the source & type of air mass that is
responsible for a nor’easter?
3. What is the source & type of air mass that can
lead to an Indian Summer?
When finished you can begin work on the NOAA
Weather Map Analysis project.
Get out your NOAA Weather Map
Bell Work Analysis handouts
In the map on the right:
1. What type of front
is shown just
south of A?
2. How will the
temperature at A
change tomorrow?
3. How was the
temperature at B
changing
yesterday?
A
B
Bell Work
Get out your notebook
for notes today
On a sheet of paper answer the following:
1. What is the difference between dew point
temperature and surface air temperature?
2. What causes a high pressure system and what
type of weather can it lead to?
3. What causes a low pressure system and what
type of weather can it lead to?
Put your name on the sheet and
leave at the top of your desk
Thunderstorms - brief, heavy
storms w/ rain, strong winds,
lightning & thunder
Thunder- the sound
made by the expansion
of air as it heats up
Lightning- an electric
discharge that takes
place water/ice particles
in clouds lose or gain an
electric charge
Conditions necessary for a
thunderstorm to occur:
1. Moisture in the lower atmosphere
2. Warm air that is rising
3. Unstable atmosphere (e.g. changing
rapidly)
Stages of a Thunderstorm
1) Developing stage warm air rises
carrying moisture (up-drafts).
Forms tall
cumulus
clouds. No rain
but lightning
can occur.
Stages of a Thunderstorm
2) Mature stage
precipitation falls
rapidly to earth
causing
downdrafts.
Winds, heavy rain,
hail, lightning and
tornadoes can
occur
Stages of a Thunderstorm
3) Dissipation
Stage:
Downdrafts become,
greater than updraft
and storm loses
energy
Severity of storm depends on balance
of updraft (rising hot air) and
downdrafts (rain/hail)
Weak updraft & weak
Downdraft:
Single-cell storm –
Typical summer
afternoon storm
Strong updraft & weak
Downdraft:
Multi-cell storm Potential for flash
flooding
Weak updraft and strong Downburst:
Microburst - violent local thunderstorm
Strong updraft and strong downdraft:
Supercell - A self-sustaining, powerful
storm with tornadoes and rain/hail
Thunderstorm Classification
1. Air-mass thunderstorms: unequal
heating WITHIN an air mass
a) Sea Breeze Thunderstorm
Cooler, heavier air moves inland
& forces warmer, lighter air up
b) Orographic Uplift Thunderstorm
Air rises due to
topography of
Earth’s surface
2. Frontal thunderstorms:
a) Advancing cold front - Form lines of
severe storms. Occur during winter to
spring transition
b) Advancing warm fronts
• Less likely to produce thunderstorms
Bell Work
1.How is the updraft stage of a
thunderstorm different from
the down draft stage?
2.How does the balance of the
updraft and the down draft
affect the severity of the
storm (give 2 examples)?
Tornado:
 Destructive, rotating column of air
 Winds up to 300 mph
 2 air masses collide - warm air spirals up
• Cold, dry, highpressure air
from northwest
• Warm, moist,
low-pressure air
from southeast
Tornado Classification:
• Enhanced Fujita Scale
(EF0 to EF5)
• Ranks based on wind
speed, duration, and
path of destruction.
• EF0: Weak tornado
• EF5: Strongest tornado
“Tornado Alley”: Midwestern US states
where cP air masses meet mT air masses.
Tornado Watch
A tornado is possible
1) Be ready to act if changes to warning
Tornado Warnings
A tornado has been sighted with winds ≥ 58
mph, hail & lightening
1) Take shelter right away – stay inside
2) Stay away from windows
Path and Strength of Tornadoes
2011 in NC
Tropical Cyclones
• Rotating, low-pressure storms
• Formed over warm ocean in
late summer
Tropical depression: winds ≤ 38 mph
Tropical storm: winds 39 to 73 mph
Hurricane/typhoon: winds ≥ 74 mph
Hurricanes
1.
2.
An intense, rotating oceanic
weather system with winds of 74
mph or greater
Occurs with rain, thunder, and
lightning
3.
4.
Forms and intensifies over tropical
oceanic regions (i.e. near the
equator).
Moves into temperate latitudes (i.e.
North Carolina).
5.
6.
7.
8.
Begin as low pressure system off
Africa
Move into the Atlantic ocean where
they grow and intensify.
Hot air near equator meets a low
pressure system → hot air rises up,
cools, then sinks → creates a
convection current
The Coriolis effect causes the winds
to curve to the right north of equator
Hurricane winds: spiral counter-clockwise in the
northern hemisphere towards a low pressure
Eye: calm center of the storm
Eyewall: wall of storms around the eye with
strongest winds
Classification of Hurricanes:
Saffir-Simpson scale (1 to 5), based on wind
speed, air pressure and potential for damage
1: weakest
hurricane
5: strongest
hurricane
Hurricane watch - hurricane
conditions possible within 36 hours
Hurricane warning - hurricane force
winds expected within 24 hours.
Tsunami
Waves created by the
displacement of a large
amount of water.
Caused by:
•
•
•
•
•
Tsunami
Earthquakes
Volcanic eruptions
Underwater explosions
Landslides
Meteorite & comet impacts in the ocean
Tidal Surges
1. The onshore rush of sea water
caused by the high winds that
accompany a hurricane.
2. Also known as “storm surge”
Tidal Surges
3. Geography of land affects strength
of the surge: shallow & narrow
inlets will have larger storm
surges.
Nor’easter (Northeastern storm)
1.
A large storm with winds that rotate
from the northeast.
2.
Causes coastal flooding and
erosion, high winds, and heavy
precipitation (blizzards inland &
rain at coast)
Bell Work
1. How are Nor’easters and hurricanes
different?
2. How are Nor’easters and hurricanes
the same?
3. How could tides and geographic
features affect a storm surge?