Weather!
Matt Aufman
NSF North Mississippi GK-8
November 2005
NSF North Mississippi GK-8
Relative Humidity
• The relative humidity tells us how “full” of
moisture the air is at the time of measurement.
•For example, 90% relative humidity means
that at that moment the air is holding 90% of
the maximum amount of water it could.
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If the air is at 100-percent relative
humidity, sweat will not
evaporate into the air. As a
result, we feel much hotter than
the actual temperature when the
relative humidity is high.
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the air’s ability to hold water
So,
vapor _____ as the temperature
of the air _____.
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SO….
air cannot hold as much _____
Cold
_____ as warm air.
Draw this.
Cold air is more dense than warm air.
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Which type of air holds more water
vapor. Warm air or cold air?
What does it mean when we say that
the relative humidity of the air is
50%, 75%, 100%?
Which type of air (cold or warm) is
heavy and dense? Why?
Which type of air (cold or warm) is
light? Why?
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Draw a picture of cold air that has a
relative humidity of 50 %. Write a
short paragraph that explains your
picture.
Draw a picture of warm air that has
a relative humidity of 70 %. Write a
short paragraph that explains your
picture.
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Cloud Cover Symbols
• You will often see
the circles drawn on
a weather map
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High and Low Pressure Areas
• High pressure • Air rises in low
causes air to sink pressure areas and
forms water
• Usually results in
droplets
several days of clear
sunny skies • Usually results in
rain and storms
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Air Masses
There are two types of air masses:
1. Continental Polar air masses
2. Maritime Tropical air masses
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Fronts
A front is the boundary separating air masses
of different densities
Fronts extend both vertically and
horizontally in the atmosphere
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Fronts: Five Types of Fronts
1. Cold Front: The zone where cold air is
replacing warmer air
• In U.S., cold fronts usually move from
northwest to southeast
• Air gets drier after a cold front moves
through
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Fronts: Five Types of Fronts
2. Warm Front: The zone where warm air is
replacing colder air
• In U.S., warm fronts usually move from
southwest to northeast
• Air gets more humid after a warm front
moves through
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Fronts: Five Types of Fronts
3. Stationary Front: When either a cold or
warm front stops moving
• When the front starts moving again it
returns to either being a cold or warm
front
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Fronts: Five Types of Fronts
4. Occluded Front: Formed when a cold
front overtakes a warm front
• This occurrence usually results in storms
over an area
• In U.S., the colder air usually lies to the
west
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Fronts: Five Types of Fronts
5. Dry Line (Dew Point Front): Boundary
separating a dry air mass from a moist air
mass
This occurrence can result in tornadoes
being formed
Usually found in western part of U.S.
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Clouds: Five Types of Clouds
1. High-Level Clouds: Usually found at
greater than 20,000 ft.
Usually made of ice crystals
Examples include Cirrus, Cirrostratus
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Clouds: Five Types of Clouds
2. Mid-Level Clouds: Usually found between
6,500 and 20,000 ft.
Usually made of water droplets, but can
be made of ice
Example is altocumulus
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Clouds: Five Types of Clouds
3. Low-Level Clouds: Usually found lower
than 6,500 ft.
Low, lumpy clouds that produce weak to
moderate precipitation
Examples include Nimbostratus and
Stratocumulus
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Clouds: Five Types of Clouds
4. Vertically developed: These clouds are thick
and puffy and extend very far upwards
Examples include Cumulonimbus and
Fair Weather Cumulus
Ordinary Cumulus clouds can quickly
become Cumulonimbus clouds that start
strong thunderstorms
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Clouds: Five Types of Clouds
5. Other: These are miscellaneous clouds
These clouds do not really fit into any
category, and all have different characteristics
Examples include billow clouds, contrails,
mammatus, orographic, and pileus
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Weather Maps: Pressure &
Temperature
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Weather Maps: Doppler Radar
Maps
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Summary
Temperature: Usually in °F, need to convert
to °C
High pressure areas cause sunny weather;
low pressure areas cause rain and storms
Two Types of air masses:
1. Continental Polar
2. Maritime Tropical
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Summary (continued)
Five types of fronts:
1. Cold
2. Warm
3. Stationary
4. Occluded
5. Dew Point (Dry Line)
Five types of clouds:
1. High Level
2. Mid Level
3. Low Level
4. Vertically developed
5. Miscellaneous
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Sources
Palmer, Chad and Evans, David. May 20, 2005. Occluded fronts can
signal weakening of storm. Accessed 28 October 2005.
http://www.usatoday.com/weather/tg/wofront/wofront.htm
Palmer, Chad and Kepple, Kevin. May 20, 2005. High-pressure
systems
brings sunny days. Accessed 27 October 2005.
http://www.usatoday.com/weather/tg/whighp/whighp.htm
Palmer, Chad and Kepple, Kevin. May 20, 2005. How low pressure
systems affect weather. Accessed 27 October 2005.
http://www.usatoday.com/weather/tg/wlowpres/wlowpres.htm
Weather World 2010, University of Illinois. No date of publication
given. Reading and Interpreting Weather Maps. Accessed 21
October 2005.
http://ww2010.atmos.uiuc.edu/(Gh)/guides/maps/home.rxml
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