[time-nuts] Weather/units question for European members

Magnus Danielson magnus at rubidium.dyndns.org
Sat May 24 09:55:06 EDT 2014


hektopascal is pseudo-SI form, as it is a compromize between the old 
milibar and propper SI unit of Pascal with suitable prefix 1 mbar = 1 
hPa, but since we have normal pressure at 1013 mbar we should write it 
as 101,3 kPa but not 1013 hPa if we is to follow SI all the way.

Temperature in C is really not strict SI, but accepted.

m/s for windspeeds is the proper unit, while km/h is only used when 
explaining high windspeeds.

Cheers,
Magnus

On 05/24/2014 02:01 PM, Javier Herrero wrote:
> Hello,
>
> Wind speed usually in meters/sec (when used for scientific data) or km/h
> (used in the news, so the people can compare with car speed ;) )
> Pressure in millibars. Meteorologist also usually refers to
> hectopascals, but it is more for representing something at a given
> altitude (for example, winds at 700hPa) than for managing pressure data.
> Temperature in ºC
> Precipitation in liters/squared meter or millimeters (it is a 1:1
> equivalence)
>
> Best regards,
>
> Javier
>
>
>
>
> On 24/05/2014 3:16, 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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