Forecasting%20the%20weather

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Forecasting the weather

• Weather The state of the atmosphere at a
  specific
  time and place.
• Meteorologist scientists who study the
  atmosphere
• Weather forecasts are issued
• to save lives
• reduce property damage
• reduce crop damage
• to let the general public know what to expect

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How far ahead can meteorologists accurately
predict the weather?

• 0-12 hrs pretty accurate except for
  unpredictable local storms.
• 12-48 hrs are able to predict which areas will
  be hit by severe storms.
• 3-5 days big events or storms can be predicted
  (hurricanes, floods).
• 6-10 days can give an average temp for a period
  of time.

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How do they do it?

• Meteorologists look at
• Existing weather conditions over a large area.
• Current data gathered from
• Satellite images
• Weather stations
• Weather balloons
• This data includes
• Atmospheric pressure
• Wind direction and speed
• Temperature of the air
• Humidity, clouds, and precipitation

• Three important factors that shape the weather
  in a given region are
• temperature
• pressure
• water

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Making a weather map

• The basic tool of a weather forecaster is the
  WEATHER MAP. 
• The weather map shows the
• distribution patterns of atmospheric pressure
• wind
• temperature and humidity
  at the different
  levels of
  the atmosphere.

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Low and High Pressure Systems

• When a cold front moves into a region and warm
  air is forced upward, an area of low pressure is
  created near Earths surface.
• A center of high pressure tends to be found where
  a stable cold air mass has settled in a region.

Remember Wind is a horizontal movement of air
from a area of high pressure to an area of low
pressure.
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Isobars

• Curved lines that indicate areas of equal air
  pressure.
• Indicate wind speed and wind direction

Closely spaced lines high change in pressure
high wind speed. Widely spaced lines slow change
in pressure low wind speed. High pressure
system (depicted by an "H") Low pressure system
(depicted by an "L
Iso equal bar pressure
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Wind

• Winds are identified as the direction FROM which
  they come.

From which direction is the wind coming
according to this wind feather?
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Weather Symbols
rain
fog

snow
haze
slight rain showers
thunderstorm
,
.
ice or snow pellets
drizzle
lightning
cloud development not observed
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about 60
no clouds
about 10
about 75
about 25
about 80
completely overcast
about 40
sky obscured
about 50