Understanding Hail Formation and Characteristics

Meteorologist Alex O'Brien explains hail formation, suspension, and measurement. The video includes an experiment using a hairdryer and ping-pong balls to demonstrate how hail stays suspended in clouds. Hail forms in thunderstorms when raindrops are lofted into cold air and freeze. Hailstones grow by collecting supercooled droplets and fall when they become too heavy. The video also covers how to measure hail size and records of the largest hailstones.

What type of clouds are primarily responsible for the formation of hail?

• Nimbostratus clouds

• Cirrus clouds

• Cumulonimbus clouds

• Stratus clouds

In the experiment with a hairdryer and ping-pong balls, what does the hairdryer represent?

• The temperature drop in the atmosphere

• The hailstone itself

• The updraft in a storm

• The downdraft in a storm

What happens to raindrops in a thunderstorm to form hailstones?

• They merge into larger raindrops

• They split into smaller droplets

• They freeze into tiny hailstones

• They evaporate and reform

What is the primary reason hailstones fall to the ground?

• The hailstones melt

• The updraft weakens

• The downdraft strengthens

• The temperature rises

What is the minimum hail size that can trigger a severe thunderstorm warning?

• Three inches

• One inch

• Two inches

• Half an inch

How can you measure the size of hail?

• Using a thermometer

• Using a ruler or comparing to common objects

• Using a barometer

• Using a hygrometer

What was the diameter of the largest recorded hailstone in the United States?

• Six inches

• Nine inches

• Eight inches

• Seven inches

What is the estimated updraft speed of the Vivian hailstorm?

• 180 to 200 miles per hour

• 160 to 180 miles per hour

• 140 to 160 miles per hour

• 100 to 120 miles per hour

What should you do if a storm with hail is approaching?

• Stay outside to observe

• Seek shelter immediately

• Drive to a higher ground

• Ignore the warnings

What is the record size of hail in Colorado?

• 4.83 inches

• 3.5 inches

• 4.0 inches

• 4.5 inches