Download Weather PPT - Killeen ISD

METEOROLOGY:
THE STUDY OF WEATHER
Weather
Instruments:
How they are
used to predict
the weather.
A Barometer measures air pressure.
Air pressure and differences in pressure are among
the most important weather makers.
The centers of storms are areas of relatively low air pressure, compared
to pressures around the storm.
High air pressure generally brings good weather.
Keeping track of how the pressure is changing is important for
forecasting the weather.
Differences in air pressure between places cause the winds
to blow - air moves from high toward low pressure.
The instruments that measure air pressure are called barometers,
from Greek words for weight and measure.
Air pressure pushes
down on the mercury
and causes the
mercury to rise.
Anemometer – measures air speed.
The cups catch the air
and spins to calculate. Wind socks are
used at many airports which
can tell speed and direction.
A weather or sounding balloon is a balloon
(specifically a type of high altitude balloon) which
carries instruments aloft to send back information on
atmospheric pressure, temperature, and humidity
by means of a small, expendable measuring device
called a radiosonde.
A rain gauge (also known as an udometer or a
pluviometer or a cup) is a type of instrument
used by meteorologists and hydrologists to
gather and measure the amount of liquid
precipitation over a set period of time.
DOPPLER RADAR
Doppler refers to the principle the Austrian scientist
Christian Doppler discovered in 1842. Doppler worked out his
ideas using sound waves, long before radio, much less radar,
was invented. But the same principle applies to radar's
radio waves and to light arriving from distant stars. The
graphics below show the basic principles behind radar and its
Doppler version.
Doppler Radar
Weather Maps
The following slide illustrates many
symbols used by weather forecasters.
We read and predict weather by using
meteorological maps. Use the legend or
keys to read symbols.
IDENTIFYING
CLOUDS
CLOUD CLASSIFICATION
• Cirrus-high level clouds that have bases
below 7,000 feet
• Cumulus- mid-level clouds that have
bases between 7000-18,000 feet
• Stratus-low level clouds that have bases
below 6,500 feet
• Vertical-tallest of all clouds that can go
up to 60,000 feet.
CIRRUS
Thin, featherlike clouds that are made of ice
crystals high in the atmosphere. Usually
means a change in the weather is coming.
CIRRUS CLOUDS (con’t)
• High altitude and wispy
• Composed of ice crystals
• Thin with hair-like strands
• Some have a wave-like
appearance
• Some have a sheet-like
appearance
• Are usually thin allowing
moonlight and sun to
shine through
CUMULUS
White and puffy clouds that
usually mean good weather.
CUMULUS CLOUDS (con’t)
• Contains ice crystals
•
•
•
•
•
or rain
Usually puffy
Noticeable vertical
development
Have popcorn appearance
Can be widely scattered
or clumped
Appears thick
STRATUS
Sheets of low, gray clouds that bring
light snow, rain, or drizzle.
STRATUS CLOUDS (con’t)
• Lowest of the low
clouds
• Appear as an
overcast, but can
be scattered
• Can be in layers
NIMBOSTRATUS
Thicker layer than stratus clouds that
completely block out the sun. They cause
steady rain or snow.
CUMULONIMBUS CLOUDS
(Vertically Formed)
Called: Thunderheads
Can produce lightning, heavy rains, hail, strong winds, and
tornados. They are the tallest of all clouds and have an
anvil shaped top due to the stronger winds at those
altitudes.
Weather Related
Natural Disasters
Bolt Lightning – created by friction with clouds
rubbing against each other causing a negative
charge on the bottom of the cloud. The ground has a positive
charge. Unlike charges (+ and -) attract each other. It
is an extremely large release of static electricity.
Tornado – a low pressure system that
rotates in a counterclockwise direction.
Damage is usually on a scale of less than a
mile across. A thunderstorm can cause
these to occur. These develop over land.
Tornado
Damage
Hurricanes – a large tropical
storm or depression that occurs
over seas or oceans close to the
equator.
Infrared
Hurricane Katrina
Hurricane
Katrina Path
Killer Avalanche