Re : Vantage Pro.

Over what interval are they measured, as the maximum rate for say 1
minute will obviously be higher than over a longer period?

--
Regards,

Paul Hyett

Vidcapper wrote:

Re : Vantage Pro.

Over what interval are they measured, as the maximum rate for say 1 minute
will obviously be higher than over a longer period?


The max rain rate displayed is based on the time taken between consecutive
bucket tips. For the VP2 sold in this country each bucket tip is 0.2 mm.
Therefore, for example, if consecutive bucket tips are 10 seconds apart this is
a rate of 1.2 mm/minute or 72 mm/hour. The rate is therfore not averaged over a
constant period of time. The heavier the rainfall the shorter the time-period
over which the max rate is measured.

--
Norman Lynagh
Tideswell, Derbyshire
303m a.s.l.

"Vidcapper" wrote in message ...

Over what interval are they measured, as the maximum rate for say 1
minute will obviously be higher than over a longer period?
=============================================

It's all explained in Application Note #28:

RAINFALL RATE
Parameters Used: Rain Total (actually, rain rate is a measured variable in
the sense that it is
measured by the ISS and transmitted to the display console, whereas all
other calculated
variables are determined by the console from data received from the ISS.)

Formula:
Under normal conditions, rain rate data is sent with a nominal interval of
10 to 12 seconds.
Every time a rain tip or click occurs, a new rain rate value is computed
(from the timer values)
and the rate timers are reset to zero.

Rain rate is calculated based on the time between successive tips of the
rain collector. The rain
rate value is the highest rate since the last transmitted rain rate data
packet. (Under most
conditions, however, a rain tip will not occur every 10 to 12 seconds.)

If there have been no rain tips since the last rain rate data transmission,
then the rain rate based
on the time since that last tip is indicated. This results in slowly
decaying rate values as a rain
storm ends, instead of showing a rain rate which abruptly drops to zero.
This results in a more
realistic representation of the actual rain event.

If this time exceeds roughly 15 minutes, than the rain rate value is reset
to zero. This period of
time was chosen because 15 minutes is defined by the U.S. National Weather
Service as
intervening time upon which one rain "event" is considered separate from
another rain "event".
This is also the shortest period of time that the Umbrella will be seen on
the display console
after the onset of rain.

===================

So rain rate is continuously being calculated according to the rules above
and transmitted to the console.

John Dann
www.weatherstations.co.uk

On 28/07/2013 20:08, General wrote:
"Vidcapper" wrote in message ...

Over what interval are they measured, as the maximum rate for say 1
minute will obviously be higher than over a longer period?
=============================================

It's all explained in Application Note #28:

RAINFALL RATE
Parameters Used: Rain Total (actually, rain rate is a measured variable
in the sense that it is
measured by the ISS and transmitted to the display console, whereas all
other calculated
variables are determined by the console from data received from the ISS.)

Formula:
Under normal conditions, rain rate data is sent with a nominal interval
of 10 to 12 seconds.
Every time a rain tip or click occurs, a new rain rate value is computed
(from the timer values)
and the rate timers are reset to zero.

Rain rate is calculated based on the time between successive tips of the
rain collector. The rain
rate value is the highest rate since the last transmitted rain rate data
packet. (Under most
conditions, however, a rain tip will not occur every 10 to 12 seconds.)

If there have been no rain tips since the last rain rate data
transmission, then the rain rate based
on the time since that last tip is indicated. This results in slowly
decaying rate values as a rain
storm ends, instead of showing a rain rate which abruptly drops to zero.
This results in a more
realistic representation of the actual rain event.

If this time exceeds roughly 15 minutes, than the rain rate value is
reset to zero. This period of
time was chosen because 15 minutes is defined by the U.S. National
Weather Service as
intervening time upon which one rain "event" is considered separate from
another rain "event".
This is also the shortest period of time that the Umbrella will be seen
on the display console
after the onset of rain.

===================

So rain rate is continuously being calculated according to the rules
above and transmitted to the console.

John Dann
www.weatherstations.co.uk

Ah - thanks for that, and to Norman for his reply too.

--
Regards,

Paul Hyett