Air Masses, Fronts and Weather Systems

Can you name the air mass?

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What is a Front?

• Fronts are boundaries that

separate air masses

• Where air masses meet and

do not mix.

Types of Fronts:

Cold Front

Occluded Front

Stationary Front

Warm Front

Note: The direction the teeth or the bumps face is the direction the front is moving

Name the front!

Name the front!

Name the front!

Name the front!

Tornadoes

Other Names for

Tornadoes

Tornado comes from the Spanish

word, tronada, which means

“thunderstorm.” Other names

for tornadoes are twisters, dust

devils, whirlwinds, waterspouts,

and cyclones.

Tornado Facts • Tornadoes are the most powerful weather phenomenon

known. A violently rotating column of air extending from a

thunderstorm to the ground. • About 80% of all tornadoes are associated with

thunderstorms and mid-latitude cyclones; the other 20% are

spawned by hurricanes that make landfall.

• Conditions for tornado formation: Cool, dry air (e.g., from the

Rockies) colliding with warm, moist air (from the Gulf). • Tornadoes can be on the ground for an instant to several hours, but the average time is 5 minutes.

On average 1000 tornadoes occur every year in the

U.S.

TORNADO Facts

• Tornadoes usually form at the rear of a thunderstorm.

• Most last less than 15 minutes.

• The funnel can vary from 40 feet to one-quarter mile.

• Winds can reach more than 260 mi/hr.

Tornado Facts

• Some monster tornadoes are a mile wide, have winds up to 300 mph, last an hour or more, and travel 200 miles.

• Tornadoes occur most often in the spring (April- June)

• Most tornadoes in the US occur along “Tornado Alley,” an area that runs from Texas to Illinois.

Pictures from Macon Tornado!

Fujita Pearson Tornado Scale • F-0: 40-72 mph, chimney damage, tree branches

broken • F-1: 73-112 mph, mobile homes pushed off

foundation or overturned • F-2: 113-157 mph, considerable damage, mobile

homes demolished, trees uprooted • F-3: 158-205 mph, roofs and walls torn down,

trains overturned, cars thrown • F-4: 207-260 mph, well-constructed walls leveled • F-5: 261-318 mph, homes lifted off foundation and

carried considerable distances, autos thrown as far as 100 meters

Hurricanes and Tornadoes – Oh My!!

What do you call it?

Hurricane Structure

A tropical storm becomes a

hurricane when its winds

exceed 73 mph.

Saffir-Simpson Scale

• Category One -- Winds 74-95 mph

• Category Two -- Winds 96-110 mph

• Category Three -- Winds 111-130 mph

• Category Four -- Winds 131-155 mph

• Category Five -- Winds greater than 155 mph

• Hurricanes can be very big! They can

be seen from outer space.

• The entire formation and life of a

hurricane takes days or weeks.

• Hurricanes usually lose power as they

travel over land.

• Hurricanes bring strong winds, heavy

rain, storm surges, flooding, and

tornadoes.

• Storm surges cause the most damage!

Hurricane Facts

Katrina Pictures!!

Review

1. Which is larger, a hurricane or a tornado?

2. Which moves faster, a hurricane or a

tornado?

3. Which lasts longer?

4. Where do hurricanes form?

5. Where do tornadoes form?

6. What do we call the area of the US that has

a high occurrence of tornadoes?

7. How long do tornadoes last?

8. How long do hurricanes last?

Venn Diagram Time

WHAT DO HURRICANES AND TORNADOES HAVE IN COMMON?

–Low Pressure

–Strong Winds

–Hazardous to Life and Property

HOW DO THEY DIFFER?

–Location

–Size

–Duration

–Season of Occurrence

–Distinctive Hazards

Location

–Hurricanes form over warm (80 °F) tropical seas

•Latitude 7-15 degrees North and South of the equator

–Tornadoes form over land in the mid-latitudes

TORNADO VS HURRICANE • Tornadoes last 15 minutes; whereas,

hurricanes can last more than a week.

• Tornadoes have a funnel that can vary in diameter from 40 feet to one-quarter mile; whereas, hurricanes can vary in diameter from 200 to 500 miles.

• The winds in a hurricane rarely exceed 150 mi/hr; whereas, the winds in a tornado can reach 260 mi/hr.

WHEN DO THEY OCCUR?

–Hurricane season

• Late Summer and Fall

–Tornado season

• Spring and Early Summer