Background Information On
Hurricane season in the Atlantic is between June
Hurricane season for the Eastern Pacific is May
To be considered a typhoon (hurricane), it must
have wind speeds of at least 119 kph.
In the western part of the North Pacific ocean
between 180° and 100°E), a hurricane is called a typhoon.
A typical typhoon (hurricane) is 600 km across.
What Causes the Storm Scientifically?
Warm moist air over the ocean rises up near the surface causing an area of low
air pressure. Air with high air pressure pushes into the area with low air pressure
and changes the low pressured air into warmer and moister air that rises as well.
As the air continues to rise, the temperature decreases and forms clouds. The
system of clouds and wind grows and spin, fed by the oceans heat and water
that evaporates. Storms north of the equator spin counterclockwise, while storms
in the south spin clockwise. The difference in the rotation is caused by the Earth’s
rotation on its axis. As the storm system rotates faster and faster, an eye
forms in the center. It is very calm and clear in the eye, with very low air
pressure. Higher pressure air from above flows down into the eye. When the
winds in the rotating storm reach 39 mph (63 kph), the storm is called a "tropical
storm." And when the wind speeds reach 74 mph (119kph), the storm is officially a
"tropical cyclone," or hurricane. Tropical cyclones usually weaken when they hit land,
because they are no longer being fed by the energy from the warm ocean waters.
However, they often move far inland, dumping many inches of rain and causing lots
of wind damage before they dissipate completely.
When Did Typhoon Haiyan Happen?
Typhoon Haiyan (Yolanda) formed
November 2, 2013 and dissipated
November 11, 2013. It struck the
Philippines on November 8, 2013.
Where Did Typhoon Haiyan Hit Hardest?
Typhoon Haiyan (Yolanda)
affected Southeast Asia;
particularly the Philippines
and parts of Vietnam and
China as well.
How Severe Was Typhoon Haiyan
Typhoon Haiyan had peak gust
speeds of 379 kph (Kilometers per
hour) while having a sustained wind
speed of about 250kph. It was a
category 5 typhoon. (In order to be
classified as a category 5 typhoon, it
has to have wind speeds over 251
How is the Severity Measured?
It is measured on the Saffir-
Simpson scale from 1-5 based
on wind speed and how much
damage was caused.
How Much Damage Was Caused?
160,000 buildings were
destroyed from Typhoon Haiyan.
384,000 acres of land was
Typhoon Haiyan dealt damage
worth $1.5 billion USD.
How Many Casualties Were There?
Killed over 6,000 people.
1,800 were reported missing.
27,000 people were reported injured.
When it happened.
Where it happened.
How many fatalities.
How hurricanes are measured.
The power of Typhoon Haiyan.
Costs, statistics, infographics.