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SEVERE
WEATHER STORMS
What is a storm?

A storm is a violent
disturbance in the
atmosphere.

Storms involve sudden
changes in air pressure,
which can cause rapid
air movement.
TORNADOES
(1)
Are rapidly whirling funnelshaped clouds that reach down
from a storm cloud to touch
Earth’s.
 Form from the same clouds that
bring thunderstorms.
 Wind speeds can reach 500
km/h (300 mph)
 These are NOT predictable.

TORNADOES (continued)

Most are about 250 feet wide
and last 15 minutes or less.
THUNDERSTORMS
(2)
These are the MOST
COMMON form of
severe weather.
 Form inside warm moist
air masses and at warm
fronts.
 Warm air is rapidly
pushed up and form huge
clouds.
 As the warm air rises, it
cools and forms dense
thunderheads.

THUNDERSTORMS (continued)
Heavy rain falls,
sometimes with hail.
 The falling rain drops
cause strong winds.

HURRICANES



(3)
Are large (can cover
several states), swirling
low pressure systems
that form over tropical
oceans.
They get their energy
from the warm waters.
They start out as
tropical storms that
grow in size and
strength.
HURRICANES (continued)
When wind speeds hit
120 km/h (75 mph)
the tropical storm is
called a hurricane.
 Cooler air sinks over
the land.
 When hurricanes
reach land, they
gradually lose strength
and slow down.

HURRICANES (yet again!!!)

Hurricanes are so large
they can be seen from
space.