You will need
- Observations about wind direction in the studied period of time, paper, pencil, ruler, eraser.
Draw two axes. Meteorologists keep records for 8 or 16 rhumbs. Depending on how detailed were the observations for wind direction, draw two, or six axes. If you were using 8 compass points (North, northeast, East, Southeast, South, southwest, West, Northwest), add two axes at an angle of 45 degrees to the first two.
Construct the bisectors to the angles of 45 degrees, when observations were conducted for 16 rhumbs. That is, if are taken into account and a more accurate direction (North-northeast, East-northeast, South-southwest, etc.), there should be two more lines.
Put all the already constructed 8-axis equal segments and connect them with lines. Find the middle of each of them through this point and the center of the picture draw a straight line. Turned four axes. Erase the auxiliary lines.
Analyze observational data. Count the number of days the wind was blowing in each direction. It is possible that in this area the air masses come only with the sample of cardinal. This means that the rose of the winds is clearly expressed.
Put on the drawn coordinate axes the results of your calculations in scale. As a rule, rose of the winds is drawn for a certain period of time: month, quarter, year. The longer the time interval, the smaller must be the scale. For example, if you build a chart for the month, then the unit can be accepted by the cell in 5 mm.
If you do a annual schedule, a single day can mean one millimeter. Take another scale that fits your needs. Measure on each axis is the number of measurement units how many days the wind was blowing in this direction.
Connect the marked points with lines. The resulting figure is the rose of the winds for a given location over a selected period of time. Light side, where stands the largest segment, characterizes the predominant direction of air masses.