BISL 04-Weather and Climate

56 METEOROLOGICAL PHENOMENA WEATHER AND CLIMATE 57

A

hurricane, with its ferocious winds, banks of clouds, and torrential

rains, is the most spectacular meteorological phenomenon of the

Earth's weather. It is characterized by an intense low-pressure

center surrounded by cloud bands arranged in spiral form; these rotate

around the eye of the hurricane in a clockwise direction in the Southern

Hemisphere and in the opposite direction in the Northern Hemisphere.

While tornadoes are brief and relatively limited, hurricanes are enormous

and slow-moving, and their passage usually takes many lives.

DEVELOPMENT

Begins to ascend,

twisting in a spiral around

a low-pressure zone

BIRTH

Forms over warm seas, aided

by winds in opposing directions,

high temperatures, humidity,

and the rotation of the Earth

1. 
   

2. 
   

Anatomy of a Hurricane

DEATH

As they pass from the sea to

the land, they cause enormous

damage. Hurricanes gradually

dissipate over land from the

lack of water vapor.

3. 
   

The high-altitude

winds blow from

outside the storm.

THE EYE

Central area,

has very low

pressure

Hurricanes in the

Northern Hemisphere

rotate counterclockwise,

and those in the

Southern Hemisphere

rotate clockwise.

VAPOR

Rises warm from the sea,

forming a column of

clouds. It rises 3,900 feet

(1,200 m) in the center of

the storm.

19 miles per hour

(30 km/h)

VELOCITY AT WHICH IT

APPROACHES THE COAST

80º F

(27º C)

is the minimum temperature

that water on the surface of

the ocean will evaporate at.

Strong ascendant

currents

Cloud bands in

the form of a

spiral

FRINGES OF STORM

CLOUDS

otate violently around

the central zone.

DANGER ZONE

The areas that are vulnerable to hurricanes in the

United States include the Atlantic coast and the coast

along the Gulf of Mexico, from Texas to Maine. The

Caribbean and the tropical areas of the western

Pacific, including Hawaii, Guam, American Samoa, and

Saipan, are also zones frequented by hurricanes.

FRICTION

When the hurricane reaches

the mainland, it moves more

slowly; it is very destructive in

this stage, since it is here that

populated cities are located.

EYE WALL

The strongest

winds are formed.

The air

wraps

around

the eye.

Descending

air currents

5

4

3

2

1

CLASSIFICATION OF DAMAGE DONE

minimum

moderate

extensive

extreme

catastrophic

CLASS 1

CLASS 2

CLASS 3

CLASS 4

CLASS 5

74 to 95 (119 to 153)

96 to 110 (154 to 177)

111 to 130 (178 to 209)

131 to 155 (210 to 250)

more than 155 (250)

4 to 5 (1.2 to 1.5)

6 to 8 (1.8 to 2.4)

9 to 12 (2.7 to 3.6)

13 to 18 (3.9 to 5.4)

more than 18 (5.4)

Saffir-Simpson category

Damage Speed miles

per hour (km/h)

High Tide

feet (m)

MAXIMUM HEIGHT

REACHED BY THE WAVES

(28 m)

92 feet/high

PATH OF THE

HURRICANE

The hurricane

begins to break

apart when it

makes landfall.

DAY 12

Now mature, it

displays a visible eye.

DAY 6

The spiral

form becomes

more defined.

DAY 3

The clouds

begin to rotate.

DAY 2

A jumble

of clouds

is formed.

DAY 1

NH

SH

SH

The trade winds

are pulled toward

the storm.

The

winds flow

outward.

Light winds give

it direction and

permit it to grow.

WIND ACTIVITY

CYCLONE

HURRICANE

TYPHOON

Equator