Water Grains?

Archive Weather Display Feature Suggestions
1

Hey Brian,
Some day when you have nothing to do, (hah!), do you think you could add the calculation for WD to display water grains?

Thanks,
Jeep

2

I might be stupid, but what are water grains?

3

Hail stones?

4

I’m with chow on this one…I have no idea what Jeep is talking about. I even did a search on google, and nothing came up. :lol: :wink:

–Tim

5

Grains is the common US measure of water hardness (the calcium/magnesium content). BUT I don’t see how WD could calculate that from any info that it has or what it’s connection might be to weather :?

6

No, water grains is a measurement of ABSOLUTE humidity, which I think is more accurate description of water vapor in the air than relative humidity.

For example relative humidity reflects the relative amount of water that air can hold at a given temperature. Change the temperature and the humidity will change even if net amount of moisture in the air remains the same. In fact a 1

7

You kinda lost me halfway through that explanation, Jeep. :lol: #-o

I don’t know too much about water grains, but it does sound legitimate argument…

–Tim

8

Interesting…

9

I think niko has a point…Just search on google “How is water hardness measured?”, and everything (that I have seen, atleast) talked about calcium/magnesium content.

While pH is a measure of acidity, hardness is a measure of how much calcium (and to a much lesser extent, magnesium) is in the water.

–Tim

10

If you search for “grains per cubic foot” which is what Jeep appears to be asking for you can find articles using that unit measure eg http://www.findarticles.com/p/articles/mi_qa3726/is_200406/ai_n9444656

11

If you do a Google search for Grains of moisture per pound you will see it is used for many things like air conditioning, crop drying, lumber dryness, dehumidifying and evaporative cooling. I tells how much moisture is in a pound of dry air at a given temperature.
Joe

12

Well, I’m glad I asked :wink:

It sounds useful …

13

For what?? :?

14

If I’ve understood it correctly, it tells you how much moisture could be in a pound of air at a given temperature. A pound of dry air doesn’t have any moisture in it at any temperature :wink:

15

i could add it as a custom tag…
i have the formula here somehwere…

16

It sounds like a nice item to have. from my search its actually called absolute humidity.

17

That would be great Brian!

Chris, you’ve no quite got it. In the example I gave,

"If outside air at 85

18

Are you sure? I thought the whole point of intercooling on turbo/super charged engines was to keep the air cooler so that it could hold more fuel, which would suggest the reverse is true.

19

But we know that to make water evaporate, you add heat. So what happens if we raise the temperature of the bowl and the surrounding air? More water will evaporate. For a while, the rate of evaporation will exceed the rate of condensation.

Eventually, though, the balance between evaporation and condensation will stabilize at the new temperature. Once again, evaporation will balance condensation. The air will again be saturated, but there will be more molecules of water vapor present in the air above the bowl. At the higher temperature, more water vapor will be present in the air at saturation. This is a good general rule to remember: the higher the air temperature, the more water vapor will be present in the air at saturation.

What happens if we lower the temperature? As the temperature is lowered, more water molecules return to the liquid state (condense) than evaporate. Eventually, at the new lower temperature, there will again be a balance between the number of molecules evaporating and the number condensing. But there will be fewer waterbowlsat.gif (2521 bytes)molecules of water vapor in the air at the new cooler temperature than were present at higher temperatures. This rule to remember is just a restatement of the previous one: the lower the air temperature, the less water vapor will be present in the air at saturation.

Relative humidity depends on two factors: the amount of moisture available, and on the temperature. So you can have a change in relative humidity in one of two ways:

  1. Change the amount of water vapor available; if there is liquid water present, for instance, a lake, you can have an increase in relative humidity by evaporation from the surface of the lake. This is pretty obvious. You
20

Very nice explanation, weatherbee! :smiley:

Hopefully that will help clear up a few things between niko and jeep. :wink:

–Tim