Download Weather Patterns

Weather Patterns
CH. 13
Weather vs. Climate
• Weather: current state
of the atmosphere
• Climate: average
weather of a particular
area over a long span of
time
Air Masses
Air mass- huge body of
air with similar
temperatures and
moisture
– Brings different weather
to an area, lasts for
several days, are
classified 2 ways:
http://player.discoveryeducation.com/index.cfm?guidAssetId=2C
AB90DA-3C54-49D0-9847AFACFBFD90CA&blnFromSearch=1&productcode=US
Classified how???
1. By their temperature
- Polar (P)
- Tropical (T)
2. By the source region over which they form.
- Continental: forms over land
- Maritime: forms over water
Can you identify the
air masses?
Air Masses and US (us or U.S. or both?)
• Most of US is affected by 2 air masses
• Continental Polar (cP) – begins in Canada and
Alaska
- cold and dry, little moisture, clear skies, lake
effect snows
• Maritime Tropical (mT)- begins in Pacific or
Atlantic Ocean
- hot temps, lots of rain, unstable air, lots of
humidity
How does cP affect Michigan in the
summer?
How does mT affects
states like Florida
and Louisiana in
the winter?
Minor Roles…
• mP- occur in winter, bring lots of snow, come
from the Pacific or the Atlantic
• cT- start in Mexico/SW US, least influence of
all air masses
• What hot dry arid states are affected by cT?
Bell Ringer 1-4-2012
• Determine the type of air mass that typically plays a
role in the weather in your area. Describe the type
of weather that is commonly associated with the air
mass and where the air mass originates. Describe
the season in your area which result from that air
mass.
• (Looks somewhere around pg. 302 and 303  )
• No you do not have to write this if you write in
complete sentences!
Bell Ringer: January 6, 2012
• Weather is a great metaphor for life sometimes it's good, sometimes it's bad, and
there's nothing much you can do about it but
carry an umbrella. ~Terri Guillemets
• What do you think about this quote?
• Is it true? Why/ why not?
Fronts
•
•
A front forms when 2 air masses meet
The 2 fronts usually move at different
speeds. There are 4 types:
1. Cold
2. Warm
3. Stationary
4. Occluded
Extra: Big diff b/w air masses causes dramatic
weather when fronts form
Warm Fronts
•
•
•
•
•
Warm air moves into an area with cooler air
A red line on the weather map:
Symbol =
Temperature difference (Temp Δ) at boundary
Moves slowly, produces rain over a large area for an
extended period
• Clouds = cirrus, cirrostratus, altostratus,
nimbostratus
• Weather gets slowly warmer with light rain and wind
• Warm Front moving in!
http://www.youtube.com/watch?v=4QPkjP7EzaI
Cloud Types
Cold Fronts
• Cold, dense air moves into an area occupied
by warmer air.
• A blue line on the weather map:
• Symbol:
• A steep face advance rapidly
• Heavy downpours, gusty winds, violent
weather, cumulonimbus clouds move quickly
• Calmer weather follows.
Cold Front video! http://www.youtube.com/watch?v=0NoPXm7d5Tc (Colorado)
Better Cold Front Video! http://www.youtube.com/watch?v=nPFMKw1_wKM
(Latvia)
Stationary Fronts
• Fronts are not overtaking, but rather moving
parallel to each other; don’t really move…
stationary!
• Red & blue on the weather map: symbol?
Extra: Very little “weather” happening if
stationary for a short time. If stationary for a
long time, warmer weather will occur
Occluded Fronts
• Cold front overtakes a warm front
• Complex weather patterns- CRAZY! And
unpredictable
Fronts, much like all of nature, do not always
behave as we would expect (they may
produce weather that varies from our
descriptions)