THE NATURE OF STORMS

Chapter 13.1

Thunderstorms Abundant source of

moisture and latent heat that maintains warmth and upward motion

The air must lift and condense, releasing the latent heat

The atmosphere must become unstable

Thunderstorm Frequency

Air-mass Thunderstorms Caused by unequal heating of the Earth’s

surface Most common in the afternoons

Frontal Thunderstorms Caused by converging warm and cold

air masses More frequent during an advancing cold

front

Stages of a Thunderstorm

SEVERE WEATHERChapter 13.2

Severe Thunderstorms Cold fronts Low pressure systems Supercells- powerful self-sustaining

storms characterized by intense updrafts

Lightning Atmospheric discharge

of electric current Heats surrounding air

to 30,000oC This superheated air

expands rapidly producing the sound we call thunder

Wind Downbursts- violent downdrafts Macrobursts- area of 5km or more;

winds of more than 200km/h Microbursts- smaller area; deadlier;

harder to predict; winds exceeding 250km/h

Hail Supercooled water freezes and collides due

to strong updrafts and downdrafts Largest hailstone on record- 7 inches wide.

That’s almost the size of a soccer ball!!

Floods Rising water due to precipitation Flash floods- runoff occurring over a

short amount of time

Tornadoes Violent, rotating column of air that

contacts the ground

Tornado Distribution

Tornado Safety

TROPICAL STORMSChapter 13.3

Tropical Cyclones Large, rotating, low-pressure storms

Formation of Hurricanes

Classifying Hurricanes

Hurricane Hazards Storm surges are caused by hurricane-

force winds driving water up and inland