How To Use A Rain Gauge To Measure Rainfall

How To Use A Rain Gauge To Measure Rainfall

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Have you ever wondered if there is a way to measure the amount of rainfall in your area? Well, it’s easier than you think and I have nine simple steps for how to use a rain gauge to measure rainfall. 

Recording such information can help you manage outdoor plants and prepare for possible storms or flooding. It can also improve the health of your lawn and garden.

Let’s look at how we can do this together.

What is a Rain Gauge?

Frog Rain Gauge

A rain gauge is a collection container used to measure rainfall amounts. It is like a personal weather station for rain. This meteorological tool provides many options and values on the precipitation at a particular place and time. It has two parts: the collector funnel and the part receiving and measuring water. 

Rain gauges do not measure the size of raindrops. If you’re a weather enthusiast who’s also curious about this, get electronic devices like a disdrometer. 

Various types of rain gauges range from basic models to automatic weather stations. Some are analog and homemade devices, while others are digital and complicated devices.

Another kind is the tipping bucket rain gauge. It also has a collector funnel that puts the rain in two small containers. The professional tipping bucket rain gauge switches sides to discharge water when reaching a certain weight. 

The number of switchovers sensed by an optical gauge is used to measure every drop of precipitation.

Another kind of rain gauge is the weighing gauge. It calculates the precipitation amount through the mass of the rain. Earlier models of this instrument used the tip of a stylus and graphic paper to record the rainfall.

What You Will Need to Follow this Tutorial

You only need a few items to learn how to use a rain gauge to measure rainfall. These include:

  • Rain gauge.
  • Pole or fence.
  • Overflow tube.
  • Bucket or any large container.

If you do not have a rain gauge, you can create a homemade rain gauge with the following materials:

  • Cylinder jar or bottle of water.
  • Clear ruler.
  • Rubber band.
  • Scotch tape.
  • Funnel.

All you have to do for this makeshift rain gauge is attach the ruler to the outside of the jar. Use a rubber band to keep the bottom of the ruler parallel to the bottom of the jar. Tape the ruler and place and add a funnel on the mouth of the jar. 

Step-by-step Guide on How to Use a Rain Gauge

Measuring rainfall amounts is not just about leaving the rain gauge and coming back after a few hours. You also need to properly mount, analyze the precipitation, and record the data. Here’s how.

1. Get to Know Your Rain Gauge

Digital rain gauges are easy to understand. They automatically measure the amount of rain and then display the measurements on the screen. 

But analog rain gauges can be more complicated. This instrument comes in the form of a tube which fills up as it precipitates. It contains lines and numbers for you to calculate the amount of rain. You can read the values by checking the number closest to the curved surface’s base. 

Some rain gauges let you record the snow’s content as well. But you need to wait for the snow to melt before getting accurate readings.

2. Decide on the Purpose of Your Rain Gauge

Rain gauge - Rain gauge - 15ml

Rain gauges are known to measure rain depth. Gardeners often use them to grow healthier plants. They keep track of the precipitation amounts as they change throughout the year. 

But you can also use them to check the dew and mist. Use your rain gauge to measure your sprinkle output and manage irrigation water. Ideally, you need 1 to 2 inches of water for gardens and lawns.

3. Set Up Your Rain Gauge

You don’t need to calibrate analog rain gauges. But this is required for digital rain gauges. 

First, install the batteries using a screwdriver to the battery compartment of the console. Place the console indoors to monitor the measurements of rainfall at different locations.

You also need to input the time setting mode of digital rain gauges, along with the alarm. Select the display mode of the rainfall to track the rate of precipitation. Choose to display the rainfall collected from a specific day, week, or month.

Some new models of rain gauges allow you to adjust the settings from your smartphone.

Other weather conditions can also show up in digital rain gauges. These include temperature and humidity levels.

4. Mount Your Rain Gauge

Closeup of rain gauge with rainwater

Place your rain gauge at the precise location for accuracy of rainfall reading. You need to consider two things here: distance and height.

Whether you have a wireless rain gauge or a direct-reading rain gauge, keep it away from any obstruction. The general guideline is to double the distance from the object’s height. For example, if there’s a 5-foot post in your yard, keep your device 10 feet away from it.

Avoid artificial precipitation-like sprinklers unless you’re using them to manage irrigation. Otherwise, placing your rain gauge near them can lead to inaccurate rainfall readings.

Once you know where to place it, mount the standard-type rain gauge 2-5 feet off the ground. You can only do this with a pole or fence. To prevent obstruction and splashback, the mouth of your rain gauge should be above the bar. Keep the top in gauge level.

5. Read the Numbers

One full tube of the rain gauge is equivalent to an inch. It is divided into tenths and hundredths for more precise recordings. These smaller parts are called increments.

The tiniest line on the tube measures 0.01 inches or one-hundredth of an inch. Think of it this way. One inch is equal to one dollar. And every small line signifies a penny or 0.01 dollars. If the water reaches the third small line, record it as 0.03, and so on. 

The longer line is the tenth place or the dime. We record it as .10, .20, and so on. When the water reaches the second big line, that is .20, 20 one-hundredths, or two-tenths inches of rain. In the lowest terms, that’s one-fifth inches of rain. 

If the rain gauge shows four-tenths of an inch of precipitation, that is equal to .30. You can also say it’s 30 one-hundredths. 

6. Look for a Curve

Young woman checking a rain gauge in a garden to keep track of precipitation and irrigation output.

The curved surface, or meniscus, is an essential part to look for when measuring rainfall. Instead of being flat, the water gets curved because there is physical contact between the water and the edges of the tube. 

So, where should you measure? Take a look at the lowest part of the curve and take your measurements from it. 

If the curve’s base is a big line between two other big lines, just add .05 inches to the value before it. So if it’s between .20 and .30, the measurement is .25 inches or 25 hundredths of an inch of rain. In simpler terms, that’s a quarter of an inch of rain.

If the curve is too low, we call this a trace of rain or “T.” Sometimes, we notice light rain falling, but the rain gauge doesn’t catch much water. Only a few millimeters of rain may have dropped if this is the case.

7. Record the Rainfall Information

Manual rain gauges do not automatically store data on rainfall levels. Therefore, you need to maintain a written record containing the observation time, and the total amount of rain or snow melted. 

You need to input the snowfall, snow depth, and snow water equivalent for snow measurements. Make sure you also have space for qualitative observations and remarks. 

Do not report dewy drops of moisture as rain. This condition is common during spring and summer, so remember to write “0.00” on these days. Despite the wet conditions, there is still an absence of rain here.

8. Record the Sprinkler Output

Automatic Lawn Sprinkler

If you’re tracking the output of the water sprinkler instead of the rainfall, wait for 30 minutes before recording. Multiply the depth of water by two so that the results are accurate for a whole hour. 

You can try minimizing the flow rate in half over thirty minutes using trial and error. Let the sprinkler run for 20 minutes if the gallon per minute doesn’t contribute to the runoff. Keep re-measuring until you reach ½.

9. When Rainfall Reaches More than One Inch

You’ll know that the rainfall has reached over an inch if the measuring tube gets full. To measure, record one inch on the rain gauge and empty it.

Ideally, you must have a larger container that catches the rest of the water spilling. It’s called the overflow tube. Pour the water into the original container one at a time and record the total. 

Perform this step gradually so as not to spill any liquid. You may also use a bucket under the tube while pouring to catch any spillage.

In Conclusion

Has this article helped you use your rain gauge correctly? Or did it help you decide on what type of rain gauge you need? We hope it did. Keeping track will help you predict the weather, manage your plants, and protect your home. It will also prepare you for heavy rainfall and potential flooding. 

Let us know what you think about rain gauges in the comments below. And if you found this article helpful, make sure to share it with your friends. And check out our other helpful guides like the best hygrometers for indoor use.

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