[time-nuts] Weather/units question for European members
brooke at pacific.net
Sat May 24 16:45:11 EDT 2014
The key benefit of an ultrasonic wind speed/direction sensor is that it can detect very slow wind speeds.
My Peet Bros. system does not start telling me anything until the speed is a few MPH.
But all the weather stations I've seen don't tell you if the wind is backing or veering and how fast that's going on.
This is critical for forecasting.
It would be possible to have a graphical display the would be like looking down on a smoke stack with the smoke trail
showing the history of wind direction.
See the Sager Weather Caster book for more on that.
Mark Sims wrote:
> I am building a weather sensor that includes a ultrasonic anemometer to measure wind speed, direction, and air temperature. It uses 4 cheap ($1 each) HC-SR04 ultrasonic rangefinder modules that output a pulse width proportional to the time of flight of the sound signal (topic is time nut related since it simultaneously measures the speed of sound in 4 directions to a pretty good accuracy/resolution using a cheap-ass microprocessor - ATMEGA328 (like and Arduino)... and does so without using any counter-timer channels).
> Now the question... I would like it to be able to output data in imperial or metric units. In what units is the typical wind speed reported (meters/sec, km/hour, ?). Also air pressure (millibars/hectopascals/pascals/?).
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