Transcript Clouds & Storms - PAMS

Clouds & Storms
Ch. 23 & 24
SOL 13 The student will investigate and understand that energy transfer between the sun and the Earth and its atmosphere drives
weather and climate on Earth. Key concepts include severe weather occurrences such as tornadoes, hurricanes, and major storms;
VBO: 3.4.5Describe the cause and effects of destructive storms such as severe thunderstorms, hurricanes, tornadoes, monsoons,
and winter storms including the proper precautionary steps to be taken.
Cloud Formation
• Cloud: small collection of water droplets or ice
crystals that form when condensation or
crystallization occurs more rapidly than
evaporation or sublimation does.
• Condensation Nuclei: Suspended particles that
provides the surface necessary for water vapor to
condense. Usually are particles of ice, dust or salt.
Classification of Clouds:
based upon their shape and altitude
Latin Vocabulary Check
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Cumulo = piled or heaped
Stratum = layered
Cirro = hair or curl
Nimbus = rain
Altus = high
Stratus
• Sheet like or layered
• Low clouds, covers large areas of the sky and
blocks sun, little precipitation
• Stratus cloud on the ground is known as fog
Nimbus
• Very dark, cause heavy precipitation
Cumulus Family
• Cumulus: Resemble cotton balls with a dark
bottom, no precipitation
• Cumulonimbus: dark storm clouds, known as
thunderheads, accompanied by rain, lightning
and thunder
Cirrus
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Composed of ice crystals
highest altitude
Commonly appear just before a snowfall or rainfall
A halo appears around the sun or moon when
viewed through a cirrus cloud. Halo is formed by
the refraction of light rays through ice crystals
3-2-1 with your shoulder partner:
Describe conditions related to 3 cloud types:
List 2 Latin names used in cloud classification:
How might an increase in 1 form of pollution (ash
particles from forest fire or volcanic eruption)
affect cloud formation?
Storms
Watch or Warning?
• Storm Watch: conditions are favorable for the
storm to develop
• Storm Warning: warns of approaching dangerous
weather. Take cover and follow safety guidelines.
Cyclones and Anticyclones?
• Cyclones – area of low pressure containing rising warm air.
Air currents start to spin. In the Northern hemisphere they
go counterclockwise and cause rainy stormy weather.
• Anticyclones – high pressure area with cold, dry air. Causes
dry clear fair weather. In the Northern hemisphere they
move clockwise.
The closer the isobars
the windier it is
Types of storms
• Storms – a violent disturbance in the atmosphere. Marked
by sudden change in air pressure and rapid air movement.
• Most common are rain and snow storms – occurs when two
fronts collide (cold meets warm)
Summer = steady rain, Thunderstorms
Winter = heavy snowfall, Blizzard = wind must reach 36
km/hr and be -7 degrees Celsius. Ice storm = rain freezes
instantly causing damage due to weight on objects
Thunderstorms
• Cold front meets warm front forming heavy rainstorms with
thunder and lightning, violent down drafts and strong wind
shear.
• May contain straight line winds (downburst): colder air being
forced down vertically in front of a storm. Once the downburst
hits the ground it has nowhere else to go, and is forced along
the ground at great speed.
• Straight-line wind damage will push debris in the same direction
the wind is blowing (hence the term straight-line).
Lightning
• Lightning – sudden discharge of electricity between
cloud and cloud; cloud and ground.
• When the air is heated by lightning it expands
quickly resulting in loud sound waves (thunder).
• Leading cause of forest fires. Can strike people,
animals, or building.
• Safety – avoid open spaces outside; don’t go under
trees for shelter, avoid sinks, bathtubs, televisions,
and telephones while inside during a lightning
storm.
Hurricanes and Typhoons
• Hurricanes – tropical cyclone that forms over tropical areas.
• Typhoon – hurricane that forms over the W. Pacific ocean.
• rapidly, spinning rising air forms a donut-shaped
wall of strong winds, clouds, and rainfall.
• The eye of the storm is calm.
• The wind reaches speeds of 74 to over 155 m/hr.
May cause serious flooding.
• Typical hurricane lasts for about 9 days and can last
for up to 3 or 4 weeks.
Most powerful of all storms.
Map of a hurricane
How are hurricanes categorized?
Anatomy of a Hurricane
Remind me to show you the
Hurricane Katrina before/after PPT
Hurricane Safety
Know the hurricane risks in your area. Learn the storm surge history and
elevation of your area.
Learn safe routes inland. Learn the location of official shelters.
Ensure that enough non-perishable food and water supplies are on
hand.
Have at least a one week supply of medications on hand.
Obtain and store materials, such as plywood, necessary to properly
secure your home.
Clear loose and clogged rain gutters and downspouts. Keep trees and
shrubbery trimmed of dead wood.
Review your insurance policy.
Make plans now on what to do with your pets should you be required to
evacuate your residence.
Tornadoes
• Destructive whirling, funnel-shaped cloud.
• Develops in low, heavy cumulonimbus clouds.
• Acts like a giant vacuum cleaner, due to the low
pressure.
• Form usually in the spring in late afternoons/
evenings.
Most common in the United States.
Map of a tornado…
More about tornadoes…
• Great Plains known as “tornado alley”
• Average diameter - .4 km
• Length traveled – 6 km for only a few minutes but winds
can still reach more than 350 km/hour.
• Houses, trains, cars, and people can all be thrown 100’s of
meters.
• Measured on the Fujita scale as F0 – F5. (five being the
strongest).
• Waterspout: Tornado in water, least damaging
Tornado alley
Debris scatters all directions
Tornado during
sunny weather
Copy and turn in for a grade 
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5.
Explain the conditions necessary for storms to form:
The relation between thunder and lightning is:
How are cyclones and anticyclones different?
A typhoon requires these conditions in order to form:
Tornadoes of the greatest strength measure what on the
fujita scale?
6. Where is tornado alley?
7. How are watches and warnings different?
8. How can a scientist interpret whether a straight-lined
wind or tornado has caused damage?
9. Optional: Do you have any additional questions or
observations that you would like to state?