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Weather!
Matt Aufman
NSF North Mississippi GK-8
November 2005
NSF North Mississippi GK-8
Temperature
• You will usually see temperature measured in
°F for maps of the United States
• Maps of foreign countries will usually be
measured in °C
NSF North Mississippi GK-8
Relative Humidity
• The relative humidity tells us how “full” 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.
NSF North Mississippi GK-8
Cloud Cover Symbols
• You will often see
the circles drawn on
a weather map
NSF North Mississippi GK-8
High and Low Pressure Areas
• High pressure
causes air to sink
• Usually results in
several days of clear
sunny skies
• Air rises in low
pressure areas and
forms water
droplets
• Usually results in
rain and storms
NSF North Mississippi GK-8
Air Masses – 4 types
Starts over land or water (dry, moist)
Starts in tropical or polar area (warm, cold)
1. Continental Polar
2.Maritime Polar
3.Continental Tropical
4.Maritime Tropical
NSF North Mississippi GK-8
NSF North Mississippi GK-8
Fronts
A front is the boundary separating air masses
of different densities
 Fronts extend both vertically and
horizontally in the atmosphere
NSF North Mississippi GK-8
Fronts: 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
NSF North Mississippi GK-8
Cold front
NSF North Mississippi GK-8
NSF North Mississippi GK-8
Fronts: 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
NSF North Mississippi GK-8
Warm Fronts
NSF North Mississippi GK-8
NSF North Mississippi GK-8
Fronts: 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
NSF North Mississippi GK-8
Fronts: 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
NSF North Mississippi GK-8
NSF North Mississippi GK-8
Fronts: 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.
NSF North Mississippi GK-8
NSF North Mississippi GK-8
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
NSF North Mississippi GK-8
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
NSF North Mississippi GK-8
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
NSF North Mississippi GK-8
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
NSF North Mississippi GK-8
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
NSF North Mississippi GK-8
Weather Maps: Pressure &
Temperature
NSF North Mississippi GK-8
Weather Maps: Doppler Radar
Maps
NSF North Mississippi GK-8
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
NSF North Mississippi GK-8
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
NSF North Mississippi GK-8
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
NSF North Mississippi GK-8