MadSci Network: Earth Sciences |
Although this question is about an anemometer, it really could apply just as easily to almost any instrument. How you would measure the maximum speed really depends on the practicalities of the output from your instrument -- what sort of gauge are you using? There are two main practical approaches to obtaining maximum/minimum readings. The first is to use a recording gauge. The wind speed measurement shows by moving a needle from right to left. So instead of the needle, let's have a pen that sits lightly on a chart mounted on a slowly rotating drum. That way we can get a chart that gives a map of just what the wind speed was at different times of the day, and it is easy to read a maximum off that. The second approach is to fit a little slider on a wire across the face of the gauge, where it will be pushed from time to time by the gauge needle. It is a bit tricky to get it exactly right. There must be enough friction that the slider will not move accidentally, nor overshoot when the needle pushes it. But the friction must be small enough that the needle can move it without being hindered in its own movement when it is trying to show the instrument reading. The idea is that you push the slider to the left at the start of the day, and every time a wind gust comes along that is a little bit bigger than anything else that has happened so far, the slider gets pushed a little further to the right. At the end of the day, the slider will be left in a position that corresponds to the speed of the fastest wind gust that day. The description of these two systems has been based on the idea that you have a mechanical read-out gauge -- a moving needle, or some similar device. If your read-out gauge is optical (rotating mirrors or similar) or electronic (output converted to an electrical voltage), you can use the equivalent ideas very much more easily.
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