Home made rain gauge

ch750536

So todays even will start in about 2 hrs I reckon. I have no scientific equipment. How can I make a reasonably reliable rain guage with typical household items or a trip to supervalu?

I fully intend to do this btw and I live in a very wet location so this could be fun.

DOCARCH

https://www.youtube.com/watch?v=QOzdcM-YZ2U

ch750536

That's brilliant. - What about wind? I can set up a camera to watch something.

ch750536

Jelly in blast cooler!

M.T. Cranium

An official rain gauge is only different from a glass jar in two respects. One is that the top opening is usually larger than the circumference of the measurement portion lower down making the measurement easier to read. The second difference is that it sits two feet off the ground and is firmly anchored by being joined to a long stake that will minimize any chance of a strong wind gust or the neighbour's dog knocking it over.

Having said that, you can get quite reliable measurements by placing a glass jar on a well-exposed picnic table top or something of similar flat surface and height off the ground. If you can only use a flat ground surface, then you're likely to get somewhat more water than fell from the sky due to splash. That might add 25% to your readings.

As long as it's the kind of glass jar that has a similar circumference to the main body below it, your rainfall reading will simply be the depth of water at the end of the storm. If your jar opening is smaller, estimate the fraction of its width relative to the main body, for example 8/10, then square that (.64) and take your final water depth multiplying by 1/r^2 in this case 1/.64 which is about 1.56.

Just make sure your exposure to the sky is good, a rough guide is that you can't find anywhere within 10 metres that has any sort of obstruction in the way of a straight fall of rain to the ground, such as large trees or buildings, rocky outcrops, garden gnomes, trampolines or fences.

Having some idea where you live from previous snow reports, I will speculate that you see 70 mm in total from this event while some nearby locations to your southwest may see 150 mm. Shannon A may see 50-60.

ch750536

Distance from house



So it's in a bucket of sand \ soil in a wheelbarrow with 50kg of ballast.

Tactical

I'll pop out my homemade rain gauge when I arrive home in the wee small hours. It can go out into a wide open area with no obstructions.

Its a copper pipe with a flat copper plate I soldered to one end.

I used car wax on the inside.

Question:-

Can I simply pour out what it collects into a measuring jug or graduated cylinder and measure or will I need to take into account the diameter of the gague?

Can I weigh the collected water and assume 1gram = 1cc and workout what fell over the period of measurement? (As a rule of thumb and not a scientific measurement taking specific gravity and temperature into account.)

FWVT

Tactical wrote: »

I'll pop out my homemade rain gauge when I arrive home in the wee small hours. It can go out into a wide open area with no obstructions.

Its a copper pipe with a flat copper plate I soldered to one end.

I used car wax on the inside.

Question:-

Can I simply pour out what it collects into a measuring jug or graduated cylinder and measure or will I need to take into account the diameter of the gague?

Can I weigh the collected water and assume 1gram = 1cc and workout what fell over the period of measurement? (As a rule of thumb and not a scientific measurement taking specific gravity and temperature into account.)

It should be pretty accurate. 1.0 mm is 1.00 litre per sq. metre or 0.001 g per sq. mm.

If you know the diameter of the pipe then calculate its area and divide that into the weight of water collected.

Rain (mm) = 0.001 × (grams of rain / area in sq. mm)

Let the water come to 20 °C before weighing it to eliminate density error. Use a digital kitchen balance.

Tactical

Deadly

Many thanks for that

I can measure the inside diameter with a vernier calipers to get an accurate measurement. Its in the region of 100mm diameter if memory serves me correct.

Tactical

My rain gauge

FWVT

Tactical wrote: »

Deadly

Many thanks for that

I can measure the inside diameter with a vernier calipers to get an accurate measurement. Its in the region of 100mm diameter if memory serves me correct.

So the area is 7855 mm². Just multiply your grams of rain by 7.855 to get mm.

Tactical

My rain gauge has been deployed this morning at 03:30.

Assuming it stays upright until I get a chance to secure it properly in the morning, I'll take a measurement tomorrow evening and post the result.

ch750536

AAaaah! I am fallen!

So in the above pic the bottle is in a bucket of sand & soil.
Starts to rain.
Bonus point to anyone who can forecast what went wrong.

ianobrien

ch750536 wrote: »

AAaaah! I am fallen!

So in the above pic the bottle is in a bucket of sand & soil.
Starts to rain.
Bonus point to anyone who can forecast what went wrong.

Sand/soil mixture absorbed rain water, changing its bulk viscosity. The sand/soil/water mixture "flowed/settled" a little, knocking over the bottle?

ch750536

ianobrien wrote: »

Sand/soil mixture absorbed rain water, changing its bulk viscosity. The sand/soil/water mixture "flowed/settled" a little, knocking over the bottle?

Almost, the bucket filled with water quicker than the rain gauge, change in densities made the bottle float, it then fell over.

Tactical

Aw, nuts.

weatherfiend

ch750536 wrote: »

Almost, the bucket filled with water quicker than the rain gauge, change in densities made the bottle float, it then fell over.

Ah hard luck!!

Tactical

FWVT wrote: »

So the area is 7855 mm². Just multiply your grams of rain by 7.855 to get mm.

For an 18 hour period my rain gauge collected 105 grams of rain.

However, that calculation gives 824mm which couldn't be correct.

Any thoughts?

blackbird99

divide the weight of water by the area 105/7.855=13.367mm

FWVT

Tactical wrote: »

For an 18 hour period my rain gauge collected 105 grams of rain.

However, that calculation gives 824mm which couldn't be correct.

Any thoughts?

Sorry, DIVIDE by 7.855! My mistake!

That gives 13.37 mm of rain

Tactical

Many thanks guys

ROHANJAIN

Home-made rain gauge:
You can find out how much rain falls where you live by making your own rain measure. This involves cutting, so you will need an adult to help.

Required Items:

• An empty plastic bottle (2 litre fizzy drink bottle would be ideal)
• Scissors
• Sticky tape
• Ruler
• Paper
• Pencil


Method:

1. Cut around the plastic bottle about two thirds of the way up.
2. Turn the top part of the bottle upside down and place it inside the bottom part - fix it in place using the tape.
3. Make a scale in centimeters on a piece of tape, using a ruler, and fix it to the side of your bottle.
4. Find a place outside to put your rain gauge. It must be open and away from trees.
5. Dig a hole and bury your rain gauge so that the top is sticking out about 5 cm out of the ground. This will stop the rain gauge from blowing down on windy days.
6. Check the rain gauge every day at the same time, measure the amount of rain collected, and empty the bottle.
7. Don't forget to write down the amount of rain collected in your weather diary.

Robxxx7

ROHANJAIN wrote: »

Home-made rain gauge:
You can find out how much rain falls where you live by making your own rain measure. This involves cutting, so you will need an adult to help.

Required Items:

• An empty plastic bottle (2 litre fizzy drink bottle would be ideal)
• Scissors
• Sticky tape
• Ruler
• Paper
• Pencil


Method:

1. Cut around the plastic bottle about two thirds of the way up.
2. Turn the top part of the bottle upside down and place it inside the bottom part - fix it in place using the tape.
3. Make a scale in centimeters on a piece of tape, using a ruler, and fix it to the side of your bottle.
4. Find a place outside to put your rain gauge. It must be open and away from trees.
5. Dig a hole and bury your rain gauge so that the top is sticking out about 5 cm out of the ground. This will stop the rain gauge from blowing down on windy days.
6. Check the rain gauge every day at the same time, measure the amount of rain collected, and empty the bottle.
7. Don't forget to write down the amount of rain collected in your weather diary.

If only i could find an adult

Tactical

Robxxx7 wrote: »

If only i could find an adult

Or some sticky tape that won't come unstuck in the rain...