wviewweather.com

chrisale · Joined: 09 Nov 2005 Posts: 187

Not sure which section this should be in.. so I'll start it here, if you think it should be somewhere else that's cool.

I've been wondering lately why the precip dials have negative values? I thought, "how can you have negative rain?!"? Then I looked at some of the other webpages in the other forum, and saw they had negative value.

Does Rain fall Up in Texas? I knew you were a little backwards down there.. but come on, it's not Australia! Wink

My real question is... using the user-image files... is there a way to change the dials so that they start at zero and perhaps have smaller increments?

I'd like to have, for example, my daily gauge go from 0 - 6cm in .5cm increments. But it seems by the example in images.c that there isn't a way to affect the increments.

Any help greatly appreciated.

(edit: I ask because today is a typical (finally!) rainy winter day in Port Alberni... already had over 42mm of rain and still going... and that's peanuts for here... but the gauge is almost PINNED! Very Happy

)

http://weather.chrisale.info

mteel · Joined: 30 Jun 2005 Posts: 435 Location: Collinsville, TX

The "Precip" dials are intended to represent Rain (minus) ET. ET is in effect negative precipitation. If you don't have a solar sensor for your Vantage Pro, they become simply rain dials. "Precip" represents "net precipitation" for a given period.

When your rain exceeds the "pegged" value of the dial, it will increase in units automatically.

There is a way for you to have 0 index "Rain" dials - develop them yourself using the "Precip" dials as a guide.

chrisale · Joined: 09 Nov 2005 Posts: 187

aahh... right, that makes sense.

A Solar radiation upgrade is on next years christmas list.

chrisale · Joined: 09 Nov 2005 Posts: 187

Right... I've figured that out now... Made the appropriate additions to the htmlGenerate.c file

Because I'm expressing my precip amount in mm instead of cm I didn't have to change any of the original dial indexes, i simply added additional indexes that started from 0 and had various scales with max values of 50, 100, 200, 500, and 1000

Had some trouble deciphering exactly how to calculate the correct value for the "baserain" and "mult" variables for each instance... but I think I've got it now.

Is there a formula you use to get those values? I initially thought 330 degrees/#values for the "mult" but I think I'm off on that.

chrisale · Joined: 09 Nov 2005 Posts: 187

one final question..

does that mean that if I were to get the ET addition then all the precip graphs would potentially reflect the "net" precipation rather than simply what's fallen from the sky?

mteel · Joined: 30 Jun 2005 Posts: 435 Location: Collinsville, TX

All that follows only pertains to the precip dials - the other dials have different scaling...

baseRain is the value at the bottom of the dial (not labeled) for a given scaling. Each tick of the dial is 30 angular degrees. It is the absolute value of that tick.

So for the case of -2.5 cm to 2.5 cm on the dial, each tick = 0.5 cm change, so the bottom tick = -3.0 cm (not displayed), total around the dial of 6 cm of rain, thus:

mult = 360/6 = 60 (degrees in circle / total cm represented)
This is number of angular degrees per cm.

baseRain = abs(-2.5 - 0.5) = abs(-3.0) = 3.0

HTH,
Mark

mteel · Joined: 30 Jun 2005 Posts: 435 Location: Collinsville, TX

There are no "Precip" Graphs - just "Precip" dials. The graphs are labeled "Rain" and only reflect rainfall. There are separate graphs for ET and Solar Radiation (see my site).

Mark

chrisale · Joined: 09 Nov 2005 Posts: 187

cool that's what I needed to know.

thanks