Download Weather Overview- Tornados Hurricanes Precipitation Floods

Weather Overview: Tornados,
Hurricanes, Precipitation, Floods, Etc
Humidity
• Humidity is the measure of the amount of
water vapor in the air.
Relative Humidity…
• The percentage of water vapor that is
actually in the air compared to the
maximum amount of water vapor the air can
hold at a specific temperature.
How is Relative Humidity
Measured?
• It is measured with a
psychrometer!
Precipitation…
• Precipitation is any form of water that falls from
clouds and reaches Earth’s surface.
• Water evaporates from every water surface on
earth and from living things. This water
eventually returns to the surface as precipitation.
• Not all clouds produce precipitation. For it to fall,
cloud droplets or ice crystals must grow heavy
enough to fall through the air. One way that cloud
droplets grow is by colliding and combining with
other droplets. As they grow larger, they move
faster and collect more small droplets. Finally, the
droplets become heavy and fall out of the cloud as
raindrops.
Types of Precipitation:
1. Rain: The most common type. They must be at
least 0.5 millimeters in diameter to be rain.
Smaller than that means that it is mist.
2. Sleet: Ice particles smaller than 5 millimeters in
diameter.
3. Freezing Rain: Falls as rain and freezes when it
hits a cold surface.
4. Snow: When water vapor in a cloud is
converted directly into ice crystals.
5. Hail: Round pellets of ice larger than 5
millimeters in diameter.
Floods..
• A flood can be small or large and they all
occur when the volume of water in a river
increases so much that the river overflows
its channel.
Flash Flood
• A sudden, violent flood that occurs within a
few hours, or even minutes, of a storm.
Storms
• A storm is a violent disturbance in the atmosphere.
They involve sudden changes in air pressure,
which in turn cause rapid air movements.
• Conditions that can bring one kind of storm can
also bring other types of storms in the same area.
Thunderstorms
• A thunderstorm is a small storm that is
often accompanied by heavy precipitation
and frequent thunder and lightning.
Lightning
• A sudden spark, or electrical discharge. As these charges
jump between parts of a cloud, between near by clouds, or
between a cloud and the ground.
• It is very similar to when you get shocked by someone
with static electricity….Just on a much larger scale.
Thunder
• A lightning bolt can heat the air near it to as much as
30,000 degrees Celsius. This is much hotter than the
surface of the sun!!! Thunder is the sound of the
explosion. Because light travels much faster than sound,
you see lightning before you hear thunder.
Tornado
• A tornado is a rapidly
whirling, funnelshaped cloud that
reaches down from a
storm cloud to touch
Earth’s surface.
How Tornados Form…
• They are most likely to occur when
thunderstorms are likely, in the spring and
early summer. A warm air mass and a cold
air mass meet. Once they meet, the cold
mass moves under the warm air, forcing it
to rise. A squall line of thunderstorms is
likely to form. A single squall line can
produce ten or more tornados.
Hurricanes
• A hurricane is a tropical cyclone that has
winds of 119 kilometers per hour or higher.
• They last for about a week and must have
warm, moist air and water to keep its
strength.
Hurricane Damage
• When they come ashore,
hurricanes cause massive
wind damage and brings
high waves. The strength
of the hurricane and
pressure raise the level of
the water up to six meters
above normal. The result
is called a storm surge or a
dome of water that sweeps
across the coast where the
hurricane lands.
Winter Storms
• Much of the precipitation in the United States falls as
snow. All year round, most begins in clouds as snow. If
the air is colder than 0 degrees Celsius or 32 degrees
Fahrenheit, the precipitation will fall as snow.
• The ability of air to hold water vapor depends on its
temperature.
• Warm air holds much more water vapor.
• Think about it…In the summer time, the weatherman
always talks about humidity but never seems to in the
winter.
Lake effect
snow