Transcript Estimating Hail Size

Severe
Weather
Foldable
COVER:
2
Name
Period
Date
1
Severe Weather:
3
Chapter 2, Section 3
Definition
Small, intense
weather systems that
produce strong winds,
heavy rain, lightning,
and thunder.
Thunderstorms
Conditions/Regions
Conditions:
• Warm air
• Moist air
• More often in summer
• Usually Cumulonimbus clouds
Regions:
• Worldwide
Thunderstorms
Formation
• Warm, moist air rises rapidly in an unstable
atmosphere
Thunderstorms
Aftermath
• Flooding
• Wind damage – branches, trees & roofs
• Lightning damage
Definition
Lightning
A large electrical discharge
that occurs between two
oppositely charged surfaces.
Lightning
Conditions/Regions
Conditions:
• Usually hot
• Usually humid
• More often in summer
• Usually Cumulonimbus clouds
Regions:
• Worldwide
Lightning
Formation
• Inside a thunderhead, electrical charges
become separated.
• Warm updrafts sweep positive charges aloft,
leaving the bottom of the cloud negatively
charged.
Lightning
Aftermath
People:
• Death – Heart attacks / 10% live
• Burns
• Memory loss
Property:
• Fire
• Damage – explosive power
• Ruin electrical products
Definition
Hailstorms
Solid precipitation that falls as
balls or lumps of ice.
Nebraska, Colorado, and Wyoming usually have the
most hail storms. The area where these three states
meet is nicknamed “Hail Alley,” and averages seven
to nine hail days per year.
Hailstorms
Conditions/Regions
Conditions:
• Spring & summer
• Warm weather
•Cumulonimbus clouds
Regions:
• Anywhere with warm air & moisture
Hailstorms
Formation
• Updraft pulls rain drops up to freezing
altitudes
• They drop and add a layer of water and the
process is repeated numerous times
• At the point the hail becomes too heavy it
falls to the ground
According to the National Weather Service, the
largest hailstone is 8 inches in diameter and
weights approximately 2 pounds.
It fell in Vivian, South Dakota on July 23, 2010
Hailstorms
Aftermath
• Broken windows
• Dents in cars
• Damage to roofs and siding of houses
•Damage to crops
•Injury to humans
Estimating Hail Size
Hail size is estimated by comparing it to a known object.
Most hail storms are made up of a mix of sizes
Pea
=
1/4 inch diameter
Marble
=
1/2 inch diameter
Dime/Penny
=
3/4 inch diameter
Nickel
=
7/8 inch
Quarter
=
1 inch
Ping-Pong Ball =
1 1/2 inch
Golf Ball
1 3/4 inches
Tennis Ball
=
=
2 1/2 inches
Baseball
=
2 3/4 inches
Tea cup
=
3 inches
Grapefruit
=
4 inches
Softball
=
4 1/2 inches
This or larger = SEVERE
Definition
Tornado
A small, rotating column of air
that has high wind speeds and
low central pressure and that
touches the ground.
Tornado
Conditions/Regions
Conditions:
• Spring & Early summer
• Cold dry air (Canada) meets warm, moist air
(Tropics)
Regions:
• Most frequently in the Great Plains & Midwest
• 75% are in the United States
Tornado
Formation
• Wind travels in two different directions causes
HORIZONTAL rotation
• Updraft
• Funnel cloud forms from vertical rotation
• Funnel cloud becomes a tornado when it
touches the ground
Tornado
Aftermath
People:
• Death – Number one cause is flying debris
• Injuries from flying objects
Property:
• Severely damaged homes & buildings
• Trees ripped out of the ground
• Roads torn up
• Crops destroyed
• Cars damaged / overturned