In meteorology, a wind vane or weather vane is an instrument which helps in determining the direction of the wind and helps in weather forecasting. Not only is it one of the oldest, but also one of the simplest weather forecasting instruments to have been invented. In fact, it is quite simple to make on your own; all you need are a few things--most of which are readily available at homes--like a drinking straw, pencil with an eraser attached to it, card paper, straight pin, and a box or a paper cup.
Step-by-step Instructions to Make a Wind Vane
The wind vane that we are referring to here is not the state-of-the-art equipment that you see at the weather station, or one that you see on tall buildings, but a simple homemade vane which is meant to help you understand the basics of wind as an element of nature.
To begin with, it is important to know that one side of the wind vane is always slightly bigger than the other. It is specifically designed in this manner to ensure that it comes in proper contact with the wind. When the wind blows, the side which is bigger is pushed by the wind, which leaves the narrower side, i.e., the pointer or arrow, pointing towards the direction from which the wind is blowing.
Take the card paper, draw the head and tail of the wind vane on it, and cut out these portions using a scissor.
An ideal design would be the shape of an arrow with a sharp nose (for the pointer) and a broad tail. Ideally, the difference in the size of these two parts should be kept minimal. This will help you keep the weight even on each side, or else the pointer will not move freely on its axis.
Take the drinking straw and give it small cuts on either end (as shown in the illustration below.)
Insert the head and tail of your wind vane in the cuts that have been made in the straw.
Take the straight pin, pierce it through the drinking straw in the center and attach the straw to the eraser on the pencil. Before you move ahead, make sure that the straw is turning smoothly.
Make a base for your wind vane using a paper cup or box. You simply have to pierce a hole in the paper cup and place the pencil in it.
Some wind vanes have directions marked on the rod of the vane, which helps the interpreter determine the direction from which the wind is blowing. In the absence of these direction pointers, the interpreter has to use a compass to determine the direction. You can either take a cardboard box with north, south, east, and west marked on it and attach it to the base of the wind vane, or, a simpler method is to use a compass as an alternative.
... if you intend to make a wind vane which you will place on the roof top, you will have to opt for wood or some metal material as these materials will withstand strong winds and rough weather conditions. In this case, you can use a marker to draw the head and tail of the wind on the material you are using and cut it with a saw. While the card paper will be replaced by wood or metal, the pencil will be replaced by a thick metal rod. If this design is carried through, then the difficulty level will also increase as you will have to resort to welding or screws to hold the equipment together.
The height of the wind vane pole will depend on where you intend to fix it. You can start by marking the area on the rod where you would mount the vane. Ideally, it should be 5 cm below the tip of the rod. Then you can take a washer and weld it on the rod, at the point marked to mount the vane. The washer will prevent your wind vane from sliding down. The next step is to attach the brackets to the back of the vane. If the vane is made of metal, you can weld these brackets, and if it is made of wood, you can use screws to fix them.
You need to make sure that the brackets are large enough to allow the wind vane to rotate freely. You will have to slip the pole in the brackets and weld another washer on the pole; this time above the vane. Ensure that the washer doesn't interfere with the movement of the vane. Once your device is ready, you can fix it on your roof top. You can also create direction pointers with letters N, S, E and W, and fix it below the vane. While fixing the vane on the roof top, you need to make sure that your direction pointers are facing in the right directions.
In order to obtain an accurate reading, you need to place the wind vane at a considerable height, in some open area, wherein buildings, trees, or other tall structures do not interfere with the wind flow. You can also attach an anemometer, i.e., a wind speed indicator, to get a precise reading.
Wind vane is often used for studying the weather. Interpreting the changes in the direction of wind and tallying it with other weather elements can help you make short range weather forecasts. If you intend to set up a home weather station and make simple weather predictions for your neighborhood, then a wind vane is definitely a must have for you. It will be your first step towards becoming an amateur meteorologist.