Download air mass

BELL RINGER 2/21/17
• Create a circle map on what you know about WEATHER
Unit 3 Air Masses and Severe
Weather
Air Pressure & Wind
• Air Pressure & Wind 2/21/2017
© Air pressure - the
pressure exerted by the
weight of air above
© Exerted in all
directions (up, down,
and sideways)
© Air pressure doesn’t just
push down on an object,
it pushes all around the
object
(High or low?)
⬜
Barometer: device
used for measuring air
pressure
⬜ Unit:
millibars (mb)
⬜ inches of mercury
Torricelli: invented the
mercury barometer in 1643
⬜
⬜
⬜
https://www.youtube.com/watch?v=GRxglLS1YWI
© The unequal heating
of earth’s surface
generates pressure
differences
© Solar radiation is the
ultimate energy
source for wind
⬜
Isobars
lines on a map that
connect places of
equal air pressure
A pressure gradient
⬜ The spacing of
isobars shows the
amount of
pressure change
over a given time
⬜
⬜
⬜ Closely spaced isobars: indicate a
steep pressure gradient and high winds.
⬜ Widely spaced isobars: indicate a
weak pressure gradient and light winds.
AKA
Pressure
Behavior
Low Pressure Centers High Pressure Centers
Cyclones
Anti-cyclones
Pressure drops
Pressure increase
Wind Behavior
Winds blow
counterclockwise
Winds blow outward and
clockwise
Weather
Associated
Severe and stormy
Fair and Sunny
Symbol
“L” that is RED
“H” that is BLUE
⬜Wind is a result of
horizontal
differences in air
pressure
⬜Air flows from
areas of high
pressure to areas
of lower pressure.
https://www.youtube.com/watch?v=aiYyCu
rh_SU
©
©
©
Jet streams are
fast-moving rivers
of air
Speed: 120 and
240 kilometers per
hour
Direction: Westto-east direction.
© https://www.youtube.com/watch
?v=WAve9PlK4Gg
© https://www.youtube.com/
watch?v=CgMWwx7Cll4
https://www.youtube.com/watch?v=huweohIh_Bw
⬜ Direction
Labeled by the direction
from which they blow
⬜ Ex: winds blowing from
the Southeast.
⬜ Tool: Wind Vane
⬜
⬜
Anemometer
⬜
Measures how fast
wind is blowing
Air Masses & Fronts
• Air Masses & Fronts 2/22
Chapter 20 Air Masses
Probing Questions
⬜ Refer back to heating of land and water activity
⬜ Now lets look at heating of land and water on a global scale! (continental and maritime)
⬜ Go back to solar radiation. Warmer at the equator. (Tropical and Polar) at equator and poles.
Air Mass
❑An air mass is a big body of air
that is characterized by similar
temps and moisture
❑When an air mass moves out of
the area it formed over, it keeps the
same temp and moisture
conditions
❑As it moves, the characteristics
of an air mass change and so
does the weather in the area it
moves over
Classifying Air Masses
⬜Air masses are
classified by
temperature and
surface area over
which they form
Classifying Air Masses
NAME
P – Polar
T – Tropical
LOCATION
High Latitudes
towards the poles
Low Latitudes
towards the equator
TEMPERATURE
Cold Temps
Warm Temps
C – Continental Over land mass
Cold or warm,
depending on the
latitude
M – Maritime
Cold or warm,
depending on the
latitude
Over water
Four Basic Types of Air Masses
cP – Continental Polar
cT – Continental Tropical
•dry
and cool
•cold and dry in winter
and summer
•dry
mT – Maritime Tropical
mP – Maritime Polar
•wet
and warm
•hot, drought-like
conditions
and warm
•wet and cold
•source of precipitation in •mild, humid, unstable
the United States
cold air from Canada
Weather in North America is influenced by
continental polar and maritime tropical air
masses
Probing Questions
Probe to get to that air masses move (wind) and the space between two air masses is the front.
Fronts
●When two air masses
meet
●boundary separating
the two air masses.
Warm Front
⬜A warm front – warm air
moves into an area
formerly covered by
cooler air
⬜Warm air glides up over a
cold, dense air mass
⬜Weather Conditions:
Light to moderate rain
Cold Front
Cold air mass moves
into an area occupied
by warmer air.
Weather Conditions:
Thunderstorms
Stationary and
Occluded Fronts
⬜stationary front:
The surface position
of the front does not
move (steady rain for
days)
⬜occluded front:
when an active cold
front overtakes a
warm front
Centers of
AKA
Pressure
Behavior
Low Pressure Centers High Pressure Centers
Low Pressure
High Pressure
Cyclones
Pressure drops
Anti-cyclones
Pressure increase
Wind Behavior
Winds blow
counterclockwise
Winds blow outward and
clockwise
Weather
Associated
Severe and stormy
Fair and Sunny
Symbol
“L” that is RED
“H” that is BLUE
​Tornadoes & Thunderstorms
• ​Tornadoes & Thunderstorms 2/23/2017
Severe Storms
-Thunderstorms
-Tornadoes
-Hurricanes
Thunderstorms
-Is a storm that generates thunder and
lightning
-Frequently produces gusty winds, heavy
rain, and hail
Associated with cumulonimbus clouds
Lightning: results
from the build up and
discharge of electric
energy between
positively (ground) and
negatively (clouds)
charged area
-Thunder: the sound
of rapidly expanding
gases usually associated
with lightning
https://www.youtube.com/watch?v=G7GbOFlFODE
https://www.youtube.com/watch?v=jM8h60S1GsM
Occurrence and Development
• Occurrence
• At any given time, there are an estimated
2000 thunderstorms in progress on Earth
• Mostly in the tropics
• Development
• Thunderstorms form when warm, humid
air rises in an unstable environment
• 3 Stages
3 Stages
•Cumulus: build up of clouds and
moisture
•Mature: Heavy rainfall, most active
time
•Dissipating: light rain, storm is
calming down
Tornadoes
⬜Tornadoes - violent
low pressure windstorms
that take the form of a
rotating column of air
(vortex).
⬜The vortex extends
downward from a
cumulonimbus
cloud producing rain
and hail
⬜Move
counterclockwise
https://www.youtube.com/watch?v=oQPBjQHG8gc
https://www.youtube.com/watch?v=V-Xbj0aEkRQ
Occurrence, Development, and
Intensity of Tornadoes
⬜Occurrence
⬜770 occur each
year
⬜Tornado Season
⬜April to June
⬜Associated with
severe
thunderstorms
⬜Intensity
⬜Fujita Tornado
scale
⬜Based on the
amount of damage
Fujita Tornado Scale
Category
Winds (MPH)
Winds (KPH)
Damage
F0
<73
<116
Light damage
F1
73-112
116-180
Moderate Damage
F2
113-157
181-254
Considerable Damage
F3
158-206
254-332
Severe Damage
F4
207-260
333-419
Devastating Damage
F5
>260
>419
Incredible and Speechless
Damage
Tornado Warnings vs. Watches
⬜Watches :
Possibility of a
tornado to be
developed in the
area
⬜Warning: Tornado
has been seen by
people or indicated
by radar
Hurricanes 2/24/2017
• HURRICANES
Hurricanes
⬜Whirling tropical cyclones (low
pressure system) producing
winds of at least 119 km per
hour (73 mph)
⬜US – Hurricanes
⬜Pacific – Typhoons
⬜Indian Ocean – Cyclones
⬜Most powerful storm on
Earth
Occurrence and
Development of
Hurricanes
Occurrence
⬜Form between 5 and 20
degrees north and south latitude
⬜Season: June 1 to November
30th
Development of Hurricanes
⬜Hurricane develop most often in
the late summer when water
temperatures are warm enough
to provide the necessary heat
and moisture to the air
⬜Low Pressure: Spins
counterclockwise
Parts of a Hurricane
Eye: Center of storm,
warmest part, winds
cease, rain ceases
Eye wall: Strongest
winds and rain
Spiral Rain Bands:
extend out from the eye
wall
https://www.youtube.com/w
atch?v=Wk_FVXVnE2I
Hurricane Intensity
⬜Storm Surge: is a dome
of water that sweep across
the coast caused by the
hurricane’s winds
⬜Categorized on the SaffirSimpson Scale (based on
wind speed)
Hurricane Warning and Watches
⬜Hurricane Watch:
could see hurricane
related hazards
within 48 hours
⬜Hurricane
Warning: Could see
hurricane winds
within 36 hours
Weather Symbols