Welcome to the Cumulus Support forum.

Latest Cumulus MX release 3.6.5 (build 3081) - 28 May 2020 (please see important announcement regarding releases since 3.5.0)
Legacy Cumulus 1 release v1.9.4 (build 1099) - 28 November 2014 (a patch is available for 1.9.4 build 1099 that extends the date range of the NOAA report and Snow Index drop-down menus to 2030)

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For discussion of DIY weather equipment - sensors, accessories, improvements to existing kit etc
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Posts: 5
Joined: Sun 12 Jun 2011 6:44 am
Weather Station: watson 8681
Operating System: vista
Location: croydon


Post by JIM »

Are they all the same ...moving magnet and switch below it to pulse when wind blows

Posts: 1069
Joined: Sat 26 Feb 2011 1:58 pm
Weather Station: Fine Offset 1080/1 & 3080
Operating System: Windows XP SP3
Location: SE London


Post by AllyCat »


By "speed", I presume you mean Windspeed. "Cup" anemometers are by far the most common type because they are reasonably accurate and linear (rotational speed proportional to windspeed), and independent of the wind direction. Similarly, magnetic sensing (reed switch or Hall sensor, etc.) of the revolutions is by far the easiest, but other methods such as optical beam interruption are sometimes used.

A few systems have used a "propeller" which is turned to face into the wind and there are other methods such as measuring the cooling of a "hot wire". But probably the most common "other" (meteorological) type uses "Ultrasonic Time of Flight": Sound waves are transmitted in two (horizontal) directions, usually at right angles, and the time taken to reach a pair of receivers is measured. Variations of the time delay indicate whether the apparent speed has been helped or hindered by the movement of the air. An advantage is that there are "no moving parts", so it's particularly suitable for adverse conditions such as mountain tops.

Cheers, Alan.

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