We're going to talk about hurricanes today. And one of the first things I want
you to know is, a hurricane is not a tornado,
okay? Those are two different things. A tornado actually, if it's over water or
over a lake is called a waterspout. So there is a difference. A hurricane
is a tropical cyclone with winds that are going to be between 119 and 320 km/h.
They can be pretty huge, 600 kilometers across is an approximation of how much
space they can take up. If it's on the west coast, and this is just sort of
a little bit different. But if it's on the west coast it's going to be called a
typhoon, okay? How does a hurricane form?
Well, it's going to begin over nice warm ocean water. And it's going to be a
low-pressure area or a tropical disturbance.
So, once meteorologists see a tropical disturbance, they are going to keep an
eye on it and watch to see if it's going to grow. If it does grow in size and
strength and get bigger,
it's going to be a tropical storm. And that's the second step. If it's a big
tropical storm, and it gets bigger and continues with higher wind speeds and
more strength, then it's going to become a hurricane. And I have
a picture that kind of gives you an idea of the parts of a hurricane.
Basically warm moist air is going to move in bands around the hurricane. And
those are like the wind bands, and you can see how those are broken up
right here. That's where you're going to see a lot of rain. The middle of
the hurricane is called the eye. And the eye of a hurricane is where the cool dry
air is, once it rises from the wind bands that are going around, it's going to rise and it's
going to cool. It will sink in the eye. And the eye is actually going to be calm.
it's really kind of cool. As the hurricane passes, it's spinning and you
can see that spinning
action. The winds will be in one direction and then as the eye passes over
the area, it will be calm. And then as the hurricane continues to move
the winds will be spinning in the other direction because it's in a circular
pattern. So an area would see both the wind in one direction, calm, and then
the wind in the opposite direction.
Hurricanes can last about a week. They can go longer than that, but a week
is generally a pretty good amount of time for it to last. And basically when
the hurricane is moving, it's getting its energy from the moist warm air
that it finds over the ocean. So when it hits land, it's basically losing its
source of energy. Then it won't take long for the storm to kind of dissipate
after it does come across land.
Damage from hurricanes can be devastating.
They have what's called a storm surge. What that is, it's a buildup with
all the heavy winds that are associated with hurricanes and rain,
it builds up water as it travels. And it's a dome of water that is
going to sweep across the coast with high waves that, as they are
coming in, can be about 6 meters high.
So we're talking about a devastating amount of water that's going to come in over top
of houses and and really cause a lot of problems in that area, there will be major flooding. I
just have a few pictures here. You can see that with the heavy winds and then the rain,
obviously there is devastation. In especially the islands, and then
Florida and that general area, is going to be hit the hardest. Here's a
picture of Hurricane Katrina and what happened with that surge of water. It
came up and in a lot of the areas you could just see the rooftops. People were going
to the tops of their houses and they were using boats to get people pulled to safety.
What do you do when a hurricane is approaching? Well the first thing you
have to pay attention to the hurricane watch and the hurricane warnings. If
there's a hurricane watch it means the conditions can
allow a hurricane to form in the next 36 hours. So that's when meteorologists are
going to be really closely watching to see what's going to happen and to see what
direction that the hurricane's going to take. With a hurricane warning the conditions are
expected within 24 hours. So when you are under a hurricane warning, it's best to
just be ready to evacuate and leave and move further inland. And that's going
to be wrapping it up for hurricanes. Make sure that you are aware of how a hurricane
forms, the wind speeds, the eye of the hurricane, the wind bands that are
surrounding it, and what kind of weather it's going to bring.