Weather Vocabulary Terms
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Adiabatic Cooling
Air Masses
Anemometer
Barometer
Blizzards & Winter Storms
Category 5 Hurricane
Cloud Types
Cold Front
Conditions For Severe Weather
Convection Cells
Convergence And Low Pressure Air
Masses
Doppler Radar And Doppler Effect
Downdrafts
Drought
Flooding
Front Types
Frontal Wedging
Gusty Surface Winds
Hurricanes And Hurricane Formation
Hygrometer
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Jet Streams
Low Vs. High Pressure Systems
Mass Evacuation
Meteorology
Reasons For The Seasons
Saffir-Simpson Hurricane Scale
Severe Weather & Seasonal Variations
Severe Weather & Societal Impacts
Severe Weather Advisory
Severe Weather Types World-Wide
Severe Weather Warning
Severe Weather Watch
Social Impacts
Storm Surge
Thunderstorm
Tornado
Tornado Safety Measures
Updrafts
Weather
Weather Maps P.335
Adiabatic Cooling
• Cooling that occurs by a
change in pressure as
an air mass rises
• Heat is not lost, but the
temperature of the air
drops as it rises in
altitude
• Usually, clouds form as
a result of the cooler
temperatures
• Responsible for cloud formation
as air rises to go over a mountain
• http://www.youtube.com/watch?
v=XH_M4jItiKw
• Windward side gets the rain,
leeward side has dry weather
(rain shadow desert)
Air Masses
• Large volume of air with
characteristics affected
by the location where it
formed
• Maritime - moist
• Continental - dry
• Polar - cold
• Tropical - warm
• 4 main air masses
affect U.S. weather
patterns
Anemometer
• device used for
measuring wind speed,
and is a common
weather station
instrument
• derived from the Greek
word anemos, meaning
wind
Barometer
• instrument that is used to
measure air pressure and
predict changes in the
weather
• Low pressure brings
clouds and bad weather
• High pressure brings clear
air and no clouds (water
droplets for clouds cannot
form under high pressure
conditions)
Blizzards & Winter Storms
• air mass of cold, dry,
Canadian air moves south
and interacts with a
warm, moist air mass
moving north from the
Gulf of Mexico
• The point where these
two air masses meet is
called a front
• A blizzard is defined by
winds blowing at 35 miles
per hour or higher. One of
the reasons why blizzards
are so dangerous is the
reduced visibility due to
snow flying everywhere
from the fast wind.
Category 5 Hurricane
• Most catastrophic
• http://www.weather.co
rating of hurricanes on
m/video/hurricaneSaffir-Simpson Scale
categories-make-adifference-38272
• Example: Katrina in New
Orleans 2005
Cloud Types
• large collection of very
tiny droplets of water or
ice crystals. The
droplets are so small
and light that they can
float in the air.
• high clouds, middle
clouds, low clouds, and
vertical clouds
• Latin Root Translation cumulus heap
stratus - layer
cirrus - wispy
nimbus - rain
Cold Front
• the transition zone
where a cold air mass is
replacing a warmer air
mass
• Warmer air moves
upward quickly and can
produce dangerous
cumulonimbus cloud
• Most dangerous and
quickly changing type of
weather front
Conditions for Severe Weather
• Types of severe weather
vary, depending on the
latitude, altitude,
topography, and
atmospheric conditions
because seasons vary by
location on the planet
• Tornado's, hurricanes,
floods and blizzards are
considered types of
severe weather
Convection Cells
• density differences
result in rising and/or
falling currents
• Can produce strong and
sudden storms
Convergence and Low Pressure Air
Masses
• Low pressure system is
an area where the
atmospheric pressure is
lower than that of the
area surrounding it
• Lows are associated with
high winds, warm air,
and atmospheric lifting.
• Lows normally produce
clouds, precipitation, and
other bad weather such
as tropical storms
• Convergence of
horizontal winds causes
air to rise
Doppler Effect & Doppler Radar
• Waves that bounce off
moving objects are
compressed
• Meteorologists can
determine which clouds
are moving away and
which are moving
towards a given
location
Downdrafts
• Downdrafts are generated
when rain-cooled, more
dense air sinks inside a
thunderstorm
• Downdrafts rapidly
transport precipitation out
of the bottom of the cloud,
and causes gusts of air to
spread out from below the
cloud. This is why it is often
very windy before a
thunderstorm arrives.
Drought
• A drought is a period of
unusually persistent dry
weather that persists long
enough to cause serious
problems such as crop
damage and/or water
supply shortages.
• Severity of the drought
depends upon the degree
of moisture deficiency,
the duration, and the size
and location of the
affected area.
• Current area of drought in
U.S.
• World-wide droughts
Flooding
• A flood is an overflow of
water that submerges
land which is usually dry
• Flash floods are usually
the most lethal.
• Slow onset floods, such
as those that hit
Bangladesh every year,
can also be lethal but
tend to give people much
more time to move to
higher ground.
Front Types
 Cold front – cold dense air
forces warm air upward
forming intense rain clouds
 Warm front – warm air
advances over cold air
forming widespread light
precipitation
 Stationary front – warm air
and cold air masses meet but
neither advances resulting in
light wind and light rain
 Occluded front – warm air is
forced upward above 2
masses of cold air resulting in
strong winds and
precipitation
Frontal Wedging
• Frontal wedging: warm
air and cold air collide,
since warm air is less
dense it is wedged
upward. This causes a
front that's usually rain.
Example: warm front
Gusty Surface Winds
• Gusty surface
winds can be
produced by
convection cells
and
thunderstorms
Hurricanes &
Hurricane Formation
• Hurricanes are
characterized
by high winds,
heavy rain,
flooding and a
storm surge
that arrives as
winds push up
offshore water
levels
Hygrometer
• hygrometer is a device
for measuring the
relative humidity of air
• simple hygrometers use
a human hair to expand
and contract as
humidity rises and falls
Jet Streams
• Polar jet streams
and subtropical jet
streams are fast
moving narrow
bands of air in the
stratosphere
• Jet streams were
discovered when
jets traveling
above the
troposphere
encountered 200
mph + winds
•
http://www.youtube.com/watch?v=CgMWwx
7Cll4
Low Pressure vs. High Pressure Systems
• Regions of sinking air are
called highs, high
pressure regions or
anticyclones. Clear skies
and fair weather usually
occur in these regions.
• Regions of rising air are
called lows, low pressure
regions, depressions or
cyclones. Clouds rain and
strong winds often occur
in these regions.
•
http://www.youtube.com/watch?v
=aiYyCurh_SU
Mass Evacuation
• Mass evacuation is
recommended for
hurricanes in order to
prevent loss of life
• Hurricanes can be
predicted early enough
to order an evacuation
of an entire region in
the path of a hurricane
Meteorology
• Meteorology - The study of the atmosphere and all
its phenomena, including weather and how to
forecast it.
Reasons for the Seasons
• Tilt of the Earth’s axis of
rotation
• Uneven heating of the
Earth
• Spherical shape of the
Earth means equatorial
region receives direct
solar rays and other
areas have sunlight
spread out
Saffir-Simpson Hurricane Scale
• The SaffirSimpson
Hurricane
Wind Scale is
a 1 to 5 rating
based on a
hurricane's
sustained
wind speed.
This scale
estimates
potential
property
damage.
Severe Weather & Seasonal Variations
• Severe weather occurs
at different locations at
different times of the
year
• This is due to seasons
Severe Weather & Societal Impacts
Drought Effects:
• Loss of food production
• Displacement as people
move from affected area
(Dust Bowl)
Effects of Hurricane
Katrina:
• Unforeseen economic effects
– Gas and Oil production shutdowns
– Unemployment
– Insurance Company
Bankruptcies
– Relocation/Flight from the
region
• Environmental Effects
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Oil Spills
Erosion
Sewage
Loss of Marine and Animal life
• Looting and Violence
Severe Weather Advisory
Conditions exist that allow for
the formation of:
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Thunderstorms
Hurricane
Flooding
Blizzard conditions
Advisories are
issued if the
weather event will
lead to nuisance
conditions
• Warning/Advisory
Indicates that a particular
weather event is imminent
or occurring. Advisories are
issued if the weather event
will lead to nuisance
conditions, while Warnings
are issued for significant
weather events which will
pose a risk to life and
property. Warnings and
Advisories are issued up to
48 hours in advance with
forecaster confidence of at
least 80%.
Severe Weather Types Worldwide
• Tornado
• Hurricane/Cyclone/Typhoon
• Drought
• Thunderstorms
• Flooding
• Blizzards
• Ice storms
• Hailstorms
Are all forms of severe weather
that occur in different
locations and in different
seasons
Severe Weather Warning
Conditions currently happening
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Thunderstorms
Hurricane
Flooding
Blizzard conditions
Warnings are issued for
significant weather
events which will
pose a risk to life and
property.
• Warning/Advisory
Indicates that a particular
weather event is imminent or
occurring. Advisories are
issued if the weather event
will lead to nuisance
conditions, while Warnings are
issued for significant weather
events which will pose a risk to
life and property. Warnings
and Advisories are issued up
to 48 hours in advance with
forecaster confidence of at
least 80%.
Severe Weather Watch
Conditions exist that allow
for the formation of:
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Thunderstorms
Hurricane
Flooding
Blizzard conditions
Weather Watch - conditions
are favorable for the
particular weather event
in and near the Watch
area, and which may pose
a risk to life and property
• Watch
Indicates that conditions
are favorable for the
particular weather event
in and near the Watch
area, and which may pose
a risk to life and property.
Watches are issued up to
48 hours in advance with
forecaster confidence
around 50%
Societal Impacts
• Severe weather can
affect:
• food production
• water resources
• fishery abundance
• public health
• economy and jobs
• For example, a drought
may occur over a few
months during a growing
season, its adverse
impacts on a society can
linger for years.
For example, a drought
may occur over a few
months during a growing
season, its adverse
impacts on a society can
linger for years.
Storm Surge
• Raised water levels that
come ashore before a
hurricane arrives
• Most deaths and
destruction are caused
by flooding associated
with storm surge
Thunderstorm
• A thunderstorm is a storm
with lightning and thunder.
Its produced by a
cumulonimbus cloud, usually
producing gusty winds, heavy
rain and sometimes hail.
All thunderstorms are dangerous. Every
thunderstorm produces lightning. While
lightning fatalities have decreased over the past
30 years, lightning continues to be one of the
top three storm-related killers in the United
States. In 2010 there were 29 fatalities and 182
injuries from lightning.
Tornado
• A tornado is a narrow,
violently rotating column
of air that extends from
the base of a
What to do in a tornado:
thunderstorm to the
ground. Because wind is
invisible, it is hard to see
a tornado unless it forms
a condensation funnel
made up of water
droplets, dust and debris.
Tornado Safety Measures
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DURING A TORNADO:
Go to a basement.
If you do not have a basement, go to
an interior room without windows on
the lowest floor such as a bathroom
or closet.
If you can, get under a sturdy piece of
furniture, like a table.
If you live in a mobile home get out.
They offer little protection against
tornadoes.
Get out of automobiles. Do not try to
outrun a tornado in your car, leave it
immediately.
If you’re outside, go to a ditch or low
lying area and lie flat in it.
Stay away from fallen power lines
and stay out of damaged areas.
http://www.weather.c
om/video/safestplace-duringtornado-35477
Updrafts
• An upward current of
warm, moist air. With
enough moisture, the
current may visibly
condense into a
cumulus or
cumulonimbus cloud.
Weather
• Weather is the
state of the
atmosphere, to
the degree that it
is hot or cold, wet
or dry, calm or
stormy, clear or
cloudy.
Weather Maps
p.355
• http://www.youtube.com/
watch?v=aiYyCurh_SU
• http://www.youtube.com/
watch?v=ivSXkmL8ZbI&list=
PL9FEF9BC1171615CA