GO 150     Weather Station Model LAB

/in /by

Name:                                                               

Introduction: Much like the concept of genus and species names, a weather station model is a set of symbols that scientists and meteorologists have agreed upon to consistently chart weather variables on a weather map. These station models are specific to the observation station where they are gathered however, they can be understood by all meteorologists due to the consistency of symbols used. The station model was invented in 1941 and has remained almost identical since then; the following weather variables can be depicted and understood from a station model: temperature, dewpoint, wind, cloud cover, air pressure, pressure tendency, and precipitation.  An example of a station model is below.

Wind speed and directions: 

Barometric trend change last three hours: 

Procedure:

  1. Type your answers in a different color or font onto this document.
  • Place your answers into the “Station Model LAB” drop box. 

Hints and techniques to interpret and draw variables

Air Pressure also known as barometric pressure:

  • Add either a 10 or a 9 in front of the number and a decimal between the last 2 digits- whichever gives you a pressure measurement within the range of 960 and 1040mb is the correct answer.

Temperature and Dew point: Are always reported in degrees Fahrenheit (°F).  Remember that the Dew Point Temperature is the temperature at which the air is full.   If air is not at the dew point then the air will have to be cooled to the dew point or the point of saturation, never heated to the dew point.   The dew point can never exceed the actual air temperature or it would mean that the air is over 100% relative humidity.   

Wind direction is measured by where the wind originates. The stick of the station models points in the direction of where the wind comes from. The flags on the stick approximate the speed of the wind, a short flag: 5 knots, a long flag 10 knots and triangle is 50 knots. A knot equals 1.85km/hr or 1.2 mph.1 knot is 1.15 mph  Please give this in mph.

Cloud cover is determined by how much of the visible sky is filled with clouds. It is usually done in estimates of 10th’s. AN obstructed view is when the observer, for some reason, could not see the sky… like at night.

Precipitation may fall to the earth in many different forms. The water equivalent (the water or melted form of the precipitation) for the last three hours is reported in the station model using inches.

Present Weather and Visibility To the left of the cloud shape in the center of the station model is the symbol depicting present weather.

The present weather symbol depicts the current weather which normally is obstructing the visibility at the time of observation. The visibility itself is shown as a number, in statute miles in the United States and meters elsewhere, describing how far the observer can see at that time. This number is located to the left of the present weather symbol.

Part 1:  Interpret the model below

  1.  Temperature:
  •  Present weather:
  • Dew point:
  • Pressure change: –
  • Pressure tendency:
  • Wind speed and direction:
  • Barometric pressure:
  • Cloud coverage:
  • Visibility:

Part 2: Create an accurate station model from the description below. Fill in the information from the text and then create the model.

Weather Report: Good morning geoscience students at Cape Girardeau, looks like we will not be breaking temperature records today! Currently, the temperature is at 95°F with a steady wind from the West, wind at 12 knots. The dew point is 90°F. If you choose to leave the air conditioning of your home and brave the heat you will see the following cloud types, cirrostratus clouds up high in the sky, stratus closest to the ground and thin altostratus in between. Cloud coverage is presently at 100%. The barometric pressure is currently at 1010.4 millibars (be sure to code this!) with a pressure change of 1.3 millibars (use the hint page) which has been continuously falling over the last three hours. Presently it is foggy reducing visibility to ¼ mile.   

  1.  Temperature
  2. Present weather:
  3. Dew point:
  4. Low cloud type:
  5. Pressure change: –
  6. Pressure tendency:
  7. Wind speed and direction:
  8. Barometric pressure:
  9. Cloud coverage:
  10. Visibility:

Part 3:

STATION MODEL DRAWING:

Part 4:  QUESTIONS:

Using the hint/technique for air pressure, decode the following:

  •  600 to millibars___________ ___________________
  • 400 to millibars ____________ ___________________  
  • 196 to millibars ____________ ___________________      

**Work backwards for the following

  • 1091.4 millibars to station model code ______________ _________________
  • 926.8 millibars to station model code_______________ ________________
  • 1002.4 millibars to station code symbol ______________ _________________
  •  Convert 7 knots to a miles per hour measurement for wind speed:
  • What is the highest dewpoint possible for an air temperature of 78°F?
  • Wind is always described by the direction in which it originates (where is comes FROM).  Draw only a wind tail for each of the following wind directions:

    Southeast                                                       North                                              Northwest

       What is the cloud cover?                  What is the cloud cover?                  What is the cloud cover?