Rain in a bucket?

[motownbrowne]

Only if it's a perfect cylinder and the rain was falling perfectly plum. But probably accurate enough to say you had a cr@p-load of rain!

I think you're right about a perfect cylinder, but I'm gonna disagree with the "falling perfectly plum" part. As long as it's coming down like it's coming down everywhere else (not in the wind eddy, rain shadow, or drip line of a tree or barn, it can come down at any angle and still read accurately.

 

[Luke'sScreenName]

I think you're right about a perfect cylinder, but I'm gonna disagree with the "falling perfectly plum" part. As long as it's coming down like it's coming down everywhere else (not in the wind eddy, rain shadow, or drip line of a tree or barn, it can come down at any angle and still read accurately.

Think about it this way...
Instead of the rain coming down crooked, imagine tipping the bucket on it's side with the rain coming straight domn plumb. Keep tilting the bucket till it's almost on its side. Can you imagine how small the area would be to catch the rain? The cylinder's open end area has not changed but the catchment area has.
I've probably failed to explain this well. I'm fairly sure I'm correct about this.

 

[Streetcar]

Think about it this way...
Instead of the rain coming down crooked, imagine tipping the bucket on it's side with the rain coming straight domn plumb. Keep tilting the bucket till it's almost on its side. Can you imagine how small the area would be to catch the rain? The cylinder's open end area has not changed but the catchment area has.
I've probably failed to explain this well. I'm fairly sure I'm correct about this.

Motown is correct. If the bucket has straight sides and away from objects that would divert wind ,the rain fall is uniform. The amount of water blowing into the bucket opening from wind would equal the amount blowing out from the wind

 

[LD1]

Agree, bucket is accurate but not being next to a building. Could be getting dripped on from the roof, could be sheltered some, if on the side the rain is hitting it would read high as some will bounce off the wall.

Most people mount rain gauges on a deck hand rail. roughly 10-12' away from the house roof which is usually ~8' or so above the deck at the gutter. Given the 40" handrail height, it would almost have to be raining sideways not to be accurate.

Me, instead of a rain gauge, I just leave a coffee cup out there. Not one of them fancy types. Just a plain straight sided cup.

Blowing rain has no effect on "average" rainfall. Make the gauge/cup/bucket level and you are accurate.

 

[motownbrowne]

Think about it this way...
Instead of the rain coming down crooked, imagine tipping the bucket on it's side with the rain coming straight domn plumb. Keep tilting the bucket till it's almost on its side. Can you imagine how small the area would be to catch the rain? The cylinder's open end area has not changed but the catchment area has.
I've probably failed to explain this well. I'm fairly sure I'm correct about this.

I do get what you're saying, but i still disagree. When we say "an inch of rain fell" we are saying that every horizontal surface received an inch of rain. Even though the opening of the bucket isn't perpendicular to the rain, it still represents the same amount of horizontal space as it would have otherwise.

I did research this, and it took longer than I thought. I'm surprised that it's not a more common question. There's lots of info about how the air current will be affected by the gauge itself and create inaccurate readings, but not as much about the angle of the collector versus the rain.

Here's the best description I could find:
newtonian mechanics - Rain measurement with wind blowing - Physics Stack Exchange

Not to boast, but according to the physics guys, my position is correct, although they do have some provisions about droplet size relative to the collector and how how real-world results will vary because of turbulence from the gauge.

 

[LD1]

Think of it this way:

To keep things simple, lets say the bucket is square and 12" by 12". Thats 1sq ft of area.

If you were to angle the bucket to match the angle the rain is falling at, you are collecting rain that would have been scattered over MORE than 1sq ft of ground.

 

[Luke'sScreenName]

Well he!!. Can't open the link from my phone but will later.
Until then I'll assume I'm wrong.
I certainly apologize if I mislead anyone with my unfounded certainty! :duh::duh:

 

[LD1]

think of it this way: and I know this is to the extreme but illustrates the principal

If the rain were blowing 100% horizontal, absolutley parallel to teh ground,

NONE of the rain would be hitting the ground. Yet with a bucket laid on its side would record a bunch of rain.

If the rain were falling at 80 degrees or 10 degrees depend on where you reference (but darn near horizontal)....Using the 12" x 12" 1 sq ft container I mentioned earlier, And collecting it in a bucket that is angled perfect with the wind.......

You would be collecting the rain that "would" have fallen on a swath of ground that were 12" wide and 69" long. So you would collect almost 6x's more rain than a 12x12 section of ground would have.

 

[4570Man]

We don't care if it is 100% accurate. All he asked is if it was fairly close.

 

[motownbrowne]

We don't care if it is 100% accurate. All he asked is if it was fairly close.

And assuming it wasn't under a drip from something else or very close to a structure, then yes, it was sort of accurate. Not precise because it doesn't have straight sides.

But c'mon, 4570 he already knew that it was accurate enough to show he got lots of rain. Rarely is something 100% accurate, but that's what discussions like this are for. We all get to expand our knowledge. I'm sorry if you don't care.