Synoptic Meteorology

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Synoptic Meteorology
Synoptic Meteorology
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Objective

• Students will analyze weather maps using
  different weather variables in order to
  determine the location of warm and cold fronts on
  a synoptic map.

What is synoptic meteorology?
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• Synoptic means
• "view together" or "view at a common point".
• The forecast weather map is for a common point in
  time, and each of the many different elements
  that create our weather (high and low pressure
  systems, fronts, and precipitation areas) can be
  viewed together.

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What are the different weather elements?

• Clouds (dewpoint moisture)
• Air masses
• Fronts
• Wind
• Pressures
• Temperature

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Clouds

• Clouds form when air is cooled to its dewpoint or
  when the air reaches saturation.
• There are four basic cloud categories observed in
  our atmosphere.

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Cloud Categories

• Cirro-form
• Nimbo-form
• Cumulo-form
• Strato-form

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Cirro-form(Mares Tails)

• High-level clouds which form above 20,000 feet
  (6,000 m) and are usually composed of ice
  crystals.
• High-level clouds are typically thin and white in
  appearance, but can create an array of colors
  when the sun is low on the horizon.
• Cirrus generally occur in fair weather and point
  in the direction of air movement at their
  elevation.

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Nimbo-form

• Nimbus comes from the Latin word meaning "rain".
• These clouds typically form between 7,000 and
  15,000 feet (2,100 to 4,600 m) and bring steady
  precipitation.
• Clouds thicken and precipitation begins to fall.

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Cumulo-form

• Clouds look like white, fluffy cotton and show
  the vertical motion of air.
• Its height will depend upon the humidity of the
  rising air.
• The tops of these clouds can reach over 60,000
  feet (18,000 m).

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Strato-form

• "Stratus" is Latin for layer or blanket.
• The clouds consist of a low layer that can cover
  the entire sky like a blanket, producing dull,
  gray weather.
• The cloud bases are usually only a few hundred
  feet above the ground.

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Air Masses

• An air mass is a large body of air with uniform
  temperature and humidity.
• Air masses can control the weather for time spans
  ranging from days to months.

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Fronts

• Fronts are the boundaries between two air masses.
  
• Fronts are classified by which type of air mass
  (cold or warm) is replacing the other.
• Warm fronts tend to be low pressure systems.
• Cold fronts tend to be high pressure systems.

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Wind

• Wind is simply air in motion.
• West winds of 10 to 20 mph (miles per hour) means
  that horizontal winds will be moving at a speed
  of 10 to 20 mph
• FROM the west.

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Pressures

• A surface map is marked with H's and L's which
  indicate high and low pressure centers.
• Surrounding these "highs" and "lows" are lines
  called isobars. "Iso" means "equal" and a "bar"
  is a unit of pressure so an isobar means equal
  pressure.
• The closer the isobars the stronger the winds.

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What do meteorologists do with these weather
elements?

• Forecasters analyze maps by hand using the
  weather elements.
• They draw smooth lines that connect the data.
• This data about weather elements is used to
  identify weather patterns and create a forecast.

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Lets begin analyzing weather maps

• You will need
• Student Data and Answer Book
• Activity 10
• Colored pencils

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Surface Pressure Map

• This map shows the sea level pressures for
  various locations in the U.S. It will help us
  identify high low pressure and wind rotation.

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• Put your black pencil on Salt Lake City, Utah
  (highlighted in blue).
• Draw a smooth line connecting all the locations
  with millibar readings of 1024.
• Remember, isobars are smooth lines.

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• The line that was drawn represents the 1024
  millibars line and you can expect the pressure to
  be 1024 millibars everywhere along that line.
• Repeat the procedure with each of the isobar
  values 1020, 1016, 1012, 1008.
• Hint There are two lines for 1016.

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Surface Pressure Map

• Your map should look like this.

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Analysis of Surface Pressure Map

• Isobars can be used to identify "Highs" and
  "Lows".
• The pressure in a high is greater than the
  surrounding air.
• The pressure in a low is lower than the
  surrounding air.
• Label the center of the high pressure area with a
  large blue "H".
• Label the center of the low pressure area with a
  large red "L".

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Your map should look like this
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• High pressure regions are usually associated with
  dry weather. As the air sinks, it warms and the
  moisture evaporates.
• High pressure Happy weather
• Low pressure regions usually bring
• precipitation. When the air rises, it cools and
  the water vapor condenses.
• Low pressure Lousy weather

H
L
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• Shade, in green, the area(s) you expect to see
  rain or snow.
• Shade, in yellow, the area(s) you expect to see
  clear skies.

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Your map should look like this
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Analysis of Surface Pressure Map

• In the northern hemisphere,
• the wind blows clockwise around centers of high
  pressure.
• The wind blows counterclockwise around lows.
• Draw arrows around the
• H on your map to indicate the wind direction.
  
• Draw arrows around the
• L on your map to indicate the wind direction.

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Your map should look like this
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Surface Temperature Map

• This map shows the air temperature for various
  locations in the U.S. The values are in F. It
  will helps us identify hot and cold weather.

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• We will begin drawing a blue line from the 40F
  temperature in Seattle, Washington (top left
  value).
• We want to connect all the 40F temperatures
  together. The nearest 40F value is located in
  Reno, Nevada, (southeast of Seattle).
• In order to get there, you must draw a line
  between the 50F temperature along the Oregon
  coast and the 30F temperature in Idaho.
• Since 40F is halfway between the two locations,
  your line from Seattle should pass halfway
  between the 50F and 30F temperatures.
• Next, connect the Seattle 40F temperature with
  the Reno 40F temperature. Your line should be
  between the 50F in Oregon and the 30F
  temperature in Idaho. Continue connecting the
  40F temperatures until you get to Texas.

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Your map should look like this.
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• Between the 60F and 30F temperatures, place a
  small dot about 1/3 the distance from the 30F
  which will represent 40F. Place another small
  dot about 2/3 the distance from the 30F which
  will represent 50F.
• Continue the isotherm line until all the 40F are
  connected.

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• Continue drawing the other isotherms at 10F
  intervals.
• Label your isotherms.

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Your map should look like this
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Analysis of Surface Temperature Map

• Isotherms are used to identify warm and cold air
  masses.
• In blue, shade the region with the lowest
  temperatures
• In red, shade the region with the warmest air.

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Your map should look like this
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Note

• Temperatures themselves are neither "cold" nor
  "hot".
• The air temperature is the measure of energy in
  the atmosphere.
• Often, television meteorologists will erroneously
  say Cold temperatures are moving in." or We
  have hot temperatures in Baltimore."
• What they should say is Cold air is moving in."
  or The weather is hot." This allows them to
  describe the air mass as indicated by the
  temperatures.

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Dew Point Temperature Map

• This map shows the dewpoint temperature for
  various locations in the U.S. The values are in
  F. It will help us identify where precipitation
  will occur.

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• Dewpoint is the temperature at which air, when
  cooled to this point, would be completely
  saturated.
• Using a green colored pencil, lightly draw lines
  connecting equal values of dewpoint temperatures
  at intervals of 10F.

Remember, like isobars, these lines (called
isodrosotherms) are smooth and do not cross each
other.
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Your map should look like this
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• In green, shade the region where dewpoint
  temperatures are 70F or greater.

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Your map should look like this
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Analysis of Dewpoint Temperature Map

• The closer the temperature and dewpoint are
  together, the greater the moisture in the
  atmosphere and the greater the chance of rain.
• Typically, dewpoints 70F or greater have the
  potential energy needed to produce severe
  weather.

Which states are more likely to have severe
weather?
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• North Carolina, South Carolina, Georgia, Florida,
  Alabama, Mississippi, Tennessee, Louisiana, and
  Texas

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Surface Pressure Change Map

• This map shows change in surface pressure (in
  whole millibars) during the past three hours at
  various locations. It will help identify fronts.

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• Using colored pencils, you will draw lines
  connecting equal values of pressure change for
  every two millibars. These lines are drawn for
  the -8, -6, -4, -2, 0, 2, 4, 6, 8, etc
  values.
• Remember, like isobars, these lines (called
  isallobars) are smooth and do not cross each
  other.

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• Using a blue colored pencil, beginning at any 2
  value, lightly draw lines connecting equal values
  of the 2 millibars pressure change.

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Your map should look like this.
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• Draw the remaining "positive" pressure change
  value(s) for 4 and 6.
• Hint 4 is not on the map.
• How do you know where to draw the lines?
• Place the 4(s) in between 3 and 5 pressure
  changes.

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(No Transcript)
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• Your map should look like this.

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• Using red colored pencils, lightly draw a line
  connecting equal pressure change values of less
  than zero (0).
• Hint Only connect the even numbered equal
  pressure change values.
• Using black, draw a line connecting the zero (0)
  line.

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• Your map should look like this.

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• In red, shade the region where the surface
  pressure change is -4 millibars or less.
• In blue, shade the region where the surface
  pressure change is 4 millibars or more.

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• Your map should look like this.

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Analysis of Surface Pressure Change Map

• A front represents the boundary of different air
  masses. A front is located on the zero line.
• Cold air is more dense than warm air.
• Before a cold front passes, the pressure falls
  steadily.
• While its passing, there is little change
  followed by a sharp rise.
• Once the front has passed, the pressure rises
  steadily.
• We can also tell where high pressure and low
  pressure systems are moving by looking where the
  greatest change is occurring.

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Draw the cold front on your map. The cold front
is located on the zero line.
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What does all of this mean?

• Analyzing maps by hand allows the meteorologist
  to study every detail of the weather.
• Detailed data can be plotted on a weather map.
• The map give current conditions and helps the
  meteorologist predict weather.

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When you put this
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with this
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and this
What is the end result?
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AN ACCURATE FORECAST!
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Discussion Questions

• Other than meteorologists, what other occupations
  might use the information contained on these
  maps?
• Why is it so important to have accurate weather
  forecasts?