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9. Wind Barbs

Objectives:

Atmospheric winds are often represented on weather maps in the form of a wind barb. Wind barb symbols give information about wind speed and wind direction in one symbol. The goal of this lesson is to teach you how to read wind barbs.

Wind barbs are composed of two components. The first is a flag pole which indicates direction. The second is a number of flags on the end of this flagpole which represents wind speeds. Commonly, the units for wind speed are expressed in knots, which is 1 nautical mile per hour. (1 knot = 1.15 mph)

The image shown on the side can be found at the UCAR site linked below. It gives an overview about how much each flag is worth and how to compute the wind speed. If you are still confused, there are other links below with more information on wind barbs.

SchoolNet8.com Online Resources:

SchoolNet8.com contains numerous maps that use wind barbs to display wind information. All of these maps use knots as their wind speed unit. One such page can be found here:

Questions:

  1. Open an archived Iowa Mesonet map from January 2nd, 2005 at 7am. The area shown on this plot is the state of Iowa. This map is called a surface plot, since it displays surface weather information. Each reporting station has a number of symbols clustered around it. Given the knowledge you have learned about wind barbs, from which direction is the wind mainly blowing from?
  2. The wind barbs also give us information about the wind speeds. Looking at the same map, can you tell what the wind speeds are at various locations in Iowa?
  3. The combination of wind speed and direction gives us an idea about where air is being moved around. The same plot gives us temperatures, which are shown in red. Can you guess if the temperatures in Central Iowa will be getting colder or warmer based solely on the wind and the temperature distribution in Iowa?

Possible Answers:

  1. For the most part, winds are from the northwest. This means if you stood at some location and faced to the northwest, the wind would be in your face.
  2. Wind speeds are around 5 to 10 knots, which is roughly 5 to 10 miles per hour.
  3. The plot indicates much colder air in Northwest Iowa with temperatures around 10 degrees, while warmer air exists in Eastern Iowa with temperatures in the mid 30s. Given the northwest flow of air, one would expect the temperature to decline in Central Iowa. Meteorologists call this process cold air advection.

Other Educational Resources:

Sites that explain wind barbs:

Other sites: