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How are hurricanes formed?

  • Hurricanes begin as tropical storms over the Atlantic and Pacific Ocean near the Equater.
  • As the moisture evaporates, it rises until, large amounts of heated moist air is then warped high into the atmophere.
  • Winds begin to circle counterclockwise North of the Equater; and then clockwise South of the Equater.
  • The peaceful centers of hurricanes are called "The Eye."
  • Twisting around it are the gathered winds ; which travel at speeds between 74 and 200 miles per hour.
  • As long as the hurricane remains over waters with the temperature of 79 farenheit or warmer it will continuously pull moisture from the surface and enlarge in size as well as force.
  • When it crosses cooler waters, it loses it's source of power and will gradually slow.

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Severe weather warnings are rare extremes in nature, that impact on human life and living space; it is vital that comunictions and decison makers have access to all weather related infomation.


What gives lightning it's zap?

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Lightning happens when the negative charges (electrons) in the bottom of the cloud are attracted to the positive charges (protons) in the ground.

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The accumulation of electric charges has to be great enough to overcome the insulating properties of air. When this happens, a stream of negative charges pours down towards a high point where positive charges have clustered due to the pull of the thunderhead.

The connection is made and the protons rush up to meet the electrons. It is at that point that we see lightning and hear thunder. A bolt of lightning heats the air along its path causing it to expand rapidly. Thunder is the sound caused by rapidly expanding air.

Three things are needed to make a blizzard.
1. Cold air (below freezing) is needed to make snow.For snow to fall to the ground, the temperature must be
cold both up in the
clouds where snowflakes form, and down at ground level. If the air near ground level is too warm, the snow will
melt on its way down, changing to rain or freezing rain.
2. Moisture is needed to form clouds and precipitation. Moisture in the air is called water vapor. Air blowing
across a body of water,
such as a large lake or the ocean, is an excellent source of water vapor. As wind moves air over the water, some
water evaporates from the surface, putting vapor into the air. This is how “lake effect snowstorms” and “Nor’easters” pick up so much moisture. However, cold air
is not able to hold much water vapor. In fact, very cold air does not make very much snow.
3. Warm, rising air is needed to form clouds and cause precipitation. For a blizzard to form, warm air must
rise over cold air. There
are two ways that this may happen. Winds pull cold air toward the equator from the poles and bring warm air
toward the poles from the equator. When warm air and cold air are brought together, a front is formed and precipitation occurs. Warm air can also rise to form clouds and blizzard snows as it flows up a mountainside.
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What Are Snowflakes?
Snowflakes are made of ice crystals. Each snowflake is made of as many as 200 ice crystals.
Some snow crystals are symmetrical, like the type that you cut from paper. They form a hexagonal shape
because that is how water molecules organize themselves as they freeze. Others are small and irregularly shaped. If they spin like tops as they fall to the ground, they may be perfectly symmetrical when they hit the Earth. But if they fall sideways, they will end up lopsided.
Even though most have a hexagonal structure, there are so many ways that water molecules can arrange
themselves as the water freezes, that some people say that there are no two snowflakes alike. Probably no two snowflakes have exactly the same arrangement of molecules.But they can look alike. Many snow crystals are like the two in the photograph below.

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How Snowflakes Form
Snowflakes form in clouds where the temperature is below freezing (0ºC, or 32ºF). The ice crystals form around
tiny bits of dirt that have
been carried up into the atmosphere by the wind. As the snow crystals grow, they become heavier and fall
toward Earth. Different types of
snowflakes form in different conditions. Temperature determines if the crystals become a flat plate, a long
column, or a prism shape.
On average, 10 inches of snow melt down to about an inch of water; however, not all snow is the same. Some
places receive very heavy
snow. For instance, only five and a half inches of January snow on Mount Washington, New Hampshire, melt
down to an inch of water.
In contrast, over 15 inches of January snow at Crested Butte, Colorado, melt down to an inch of water.

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* When meteorologists forecast a winter storm one of the important questions they must answer is what type of
precipitation is going
  • to fall (rain, snow, sleet, or freezing rain)?
Look at the graphs below. Decide how precipitation changes form as it falls through the air at different temperatures from the upper levels of the atmosphere to the ground.
    • Four profiles of temperature with 0°C line:

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Forecast the precipitationSnow
Freezing Rain

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Forecast the precipitation:Snow
Freezing Rain

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Forecast the precipitation:Snow
Freezing Rain

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Forecast the precipitation:Snow
Freezing Rain

Other Icy Precipitation
Snow is not the only type of ice that falls from the sky! Other types are described below.
Graupel: Snowflakes that have become encrusted with ice. This happens when snowflakes pass through a
chilly cloud on their way down
and water droplets freeze on them.
Ice pellets: Frozen raindrops, also known as sleet. They are usually quite small in size and unlike snowflakes,
do not have a crystal shape.
external image golfball%20hail%20NOAA.jpgHail: A frozen raindrop or graupel that is kept from falling to the ground by the upward flowing air of a
thunderstorm. The more droplets that freeze onto the hailstone, the longer the hailstone spends in the sky.
When it finally grows too heavy to be
held up by the flowing air, it falls to the ground.

A flood is an over flow of water which covers land which is usally dry.There are 2 types of floods :inland and coastal.Most inland floods happen when there has been heavy rain or when a lot of snow melts. The water swells rivers and creeks and makes them overflow their banks. Coastal floods are caused by high tides, a rise in sea level, storm waves and on-shore winds .


All clouds are made up of tiny water droplets and ice crystals. Water has a unique trait. It has the ability to change from a vapor to a liquid to a solid and back again! When water changes form, scientist say that "it changes phase."

phase changes in H2O
phase changes in H2O

When water changes phase from a liquid (water) to a solid (ice) we call this "freezing." When it changes from a solid (ice) to a liquid (water) we call this "melting."

===The water molecules in this glass of liquid water are all moving around at different speeds and in different directions. At the surface, some of these molecules are moving fast enough and in the right direction to escape into the air. When the molecules do this, the water is evaporating.===

If we heat the water, the liquid water molecules will move even faster. This will increase the amount of evaporation taking place at the liquid's surface.


To reverse the evaporation process, we can cool the air above the glass of water. If we do this, the water vapor molecules in the air slow down. As they slow down, some molecules are not able to maintain their vapor form. They cluster (condense) in the air to form tiny liquid droplets.

A cloud is composed of tiny water droplets (or ice crystals) that are suspended in the air. If the droplets become large enough,they may be visible as a cloud or fog.They may also fall to Earth in the form of rain (or snow).

Can you explain how the speed of water molecules applies to the process of freezing and melting?

low clouds: stratus
low clouds: stratus
middle clouds: altostratus
middle clouds: altostratus
high clouds: cirrus
high clouds: cirrus

Low clouds= Stratus Middle clouds= Altostratus High clouds= Cirrus Vertical development=Cumulus

cloud altitude chart
cloud altitude chart


FASCINATING FACTGiant waves,called tsunamis, are caused by earthquakes beneath the ocean . when the waves reach the shore they crash suddenly and cause great damage.The tallest recorded tsunami was as tall as a 25 storey building.

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