Download Severe Weather - mrnicholsscience

Severe Weather
--for those who know enough to
come in out of the rain.
Flash flooding
Tornado
High winds
Lightning
Thunderstorm
Hurricane
Winter storms
• Over 500 Americans die each year due to
weather related incidents.
• Billions of dollars of damage is done to
American homes, farms, cities, and
businesses
Rule 1
• Warm air tends to…
Rule 1
• Warm air tends to rise!
Just like warm water and warm magma
Convective uplift—it is forced up
by the cooler (and therefore more
dense) fluid around it.
Four reasons air might rise:
1.
2.
3.
4.
Four reasons air might rise:
1. Convective uplift
2. Orographic uplift
3. Frontal wedging
4. Convergence
Four reasons air might rise:
1. Convective uplift
--less dense air is forced up by surrounding air
2. Orographic uplift
--if the land surface rises, the air has to rise
3. Frontal wedging
--an air mass forces its way under another mass
4. Convergence
--when two air masses come together, the only
way to go is up
Air Masses
• --like water masses.
• A body of air with its own temperature
and humidity
Air Masses
• --like water masses.
• A body of air with its own temperature
and humidity
Continental (dry) or
Maritime (humid)
Polar (cold) or
Tropical (warm)
Front-where two air masses meet
• Cold air mass
(moving southeast)
Warm air mass
(moving east)
Warm air mass
Cold
air
mass
Fronts
When a front advances…
When a front advances…
• …one air mass goes over the other.
• The warmer air mass usually goes over
the other.
Clouds form…
Clouds form…
• …when an air mass
cools enough to allow
the water vapor to
condense.
• When a warm air mass
rises, it starts to cool due
to expansion—air
pressure is less up there
Cold Air
mass 
Clouds form…
• …or they don’t.
• Water vapor is clear and colorless-Air has water vapor.
Clouds have water droplets.
Clouds form…
• …or they don’t.
• Water vapor is clear and colorless-Air has water vapor.
Clouds have water droplets.
Condensation nuclei make it more likely that water
vapor can condense into water droplets
Cumulus clouds make thunderstorms
Cumulonimbus clouds (raining)
Air movement in a thunderstorm
Types of clouds
• Basically—three types are important:
• Stratus
• Cumulus and
• Cirrus
Types of clouds
• Basically—three types are important:
• Stratus means “a layer”
• Cumulus and
means “heaped”
• Cirrus
means “wispy”
Types of clouds
• Basically—three types are important:
• Stratus
• Cumulus and
• Cirrus
Nimbus = “raining”
Alto = “high”
Combination types take both names
Types of clouds
Types of clouds
Cirrus clouds
Stratus clouds
Cumulus clouds
Cumulonimbus
Cumulonimbus
Complete
numbskull
Above the clouds
Above
the
clouds
Weather
occurs in the
troposphere
Above
the
clouds
Air cools as
you get
higher
Above
the
clouds
Top of Mt.
Everest
Above
the
clouds
The
tropopause is
the top of the
troposphere
Above
the
clouds
Highest
clouds
Above
the
clouds
Passenger
jets fly here
Above
the
clouds
Propeller
plane altitude
record
Above
the
clouds
Jet plane
altitude
record
Above
the
clouds
Air doesn’t
get cooler
with altitude
in the
stratosphere
Above
the
clouds
Ozone layer
Cooling with
altitude, again
Above
the
clouds
NASA gives
astronaut’s
wings above
the
mesopause
Above
the
clouds
Northern
lights
Above
the
clouds