Weather Station Models

1
Weather Station Models

• Meteorologists use a system of assignment and
  coding to report a variety of weather conditions
  at a single location on a weather map.

2
What do Weather Map Symbols look like?

• Open to p. 13 of your reference table.

3
What does a weather station tell us?

• The sky around the weather observation station
  including the amount of cloud cover
• The present weather conditions including
  precipitation type and amount.
• The visibility (measured in miles)
• The air temperature and dew point (both in
  degrees Fahrenheit
• The wind speed and direction
• The barometric pressure (measured in millibars)
  and the pressure trend.

4
Cloud Cover

• Cloud cover is represented by a pie graph. The
  amount of the circle that is dark is used to
  indicate the portion of the sky covered by
  clouds. It can be empty (0), shaded by 25,
  50, 75 or 100.

5
Temperature

• Temperature, also known as dry bulb temperature,
  will always be the first number written on the
  upper left hand side of the model. It is always
  recorded in Fahrenheit.

6
Visibility

• This indicates the greatest distance, measured in
  miles, at which objects can be identified.

7
Present Weather

• This term describes the atmospheric conditions
  such as precipitation or limited visibility. The
  present weather symbols shown in the box below
  are examples of what can be indicated on the
  weather station model.

8
Dew Point

• Dew point is the temperature at which the air
  would be saturated with water vapor. Although
  dew point is a temperature it is an indicator of
  the absolute humidity. In this model, the dew
  point of 27 degrees F is very close to the air
  temperature of 28 degrees F. This indicates a
  high humidity.

9
Wind Direction

• A line connected to the circle indicates wind
  direction. Remember wind is always named
  according to the direction it is coming from. In
  this example the wind direction is south-west.

10
Wind Speed

• Small lines at the end of the wind indicator are
  called feathers. This example is a 15 knot wind.
  As printed on the chart 1 knot1.15 mph.
  (highlight this)

11
Precipitation

• The amount of rain or snow in the past 6 hours is
  sometimes shown. In the model below, the weather
  station has received an amount of snow equivalent
  to one-quarter of an inch of rainfall.

12
Barometric Trend

• Rising air pressure usually brings clearing
  weather. Stormy weather is more likely if the
  atmospheric pressure is going down. A
  indicates rising air pressure and a indicates
  falling air pressure over the last three hours.

13
Barometric Trend (continued)

• The number on the weather station is in milibars
  and tenths of millibars. You need to insert a
  decimal between the two numbers. For example if
  asked what is the barometric trend you would say
  a steady rise of 1.9 mb in the past three hours.

14
Barometric Pressure

• Barometric (air) pressure is recorded as a three
  digit number. It helps to realize that the
  normal barometric pressure at Earths surface is
  generally 1000 millibars (mb).

15
How to Interpret Barometric (Air) Pressure

• Study This!!!!!!
• If the three digit code is less than 500 (499 or
  less) add a 10 at the beginning and a decimal
  point before the last number.
• If the three digit code is greater than 500
  (500) add a 9 before the number and a decimal
  before the last digit.

16
Lets Practice

• Complete handout (question one see handout)

17
Question 2

• 2) Draw a station model to represent the
  following conditions
• Temperature and dew point are 62 degrees
  Fahrenheit
• There is fog
• Visibility is only 1/10 of a mile
• Winds are from the west at 10 knots
• The air pressure is 1002.0 millibars and it has
  gone down steadily 0.9 millibars in the past
  three hours.
• Cloud cover is 25.

18
Question 3

• Draw a station model to indicate
• A temperature of 20 degrees Celsius
• A dew point of 11 degrees Celsius
• Clear Skies

19
Summary

• Complete questions 27 28 on p. 157 of your
  regent review book.