Rainfall Measurement: Understanding and Calculating in Centimeters
Every year, millions of meteorologists and hydrologists around the world rely on accurate rainfall measurements to understand precipitation patterns and make informed decisions regarding water management. These measurements are typically recorded in millimeters (mm) or centimeters (cm). In this article, we will explore the process of measuring rainfall and how to convert millimeters to centimeters. Additionally, we will discuss the equipment used for rainfall measurement and how to create your own rain gauge for personal or educational use.
Understanding Rainfall Units
Rainfall is generally measured in two common units: millimeters (mm) and centimeters (cm). It's important to note that 1 cm is equivalent to 10 mm of rainfall.
Conversion from Millimeters to Centimeters
To convert millimeters to centimeters, you can follow these simple steps:
Collect Rainfall Data
The first step in measuring rainfall is to collect the total amount of rain that falls over a specific period using a rain gauge, also known as a rain gauge. These devices can vary in design but are typically funnel-shaped containers that collect rainwater and direct it into a measuring cylinder.
Measure the Rainfall
After a rain event, check the water level in the gauge. This measurement is usually in millimeters.
Convert to Centimeters
To convert the rainfall measurement from millimeters to centimeters, divide the number of millimeters by 10.
Example Calculation
If a rain gauge shows 50 mm of rainfall, the calculation for centimeters would be:
50/10 5 cm
This simple conversion is particularly useful in meteorology and hydrology, where precise measurements of precipitation levels are essential for reporting and analysis.
The Rainfall Measurement Process
Rainfall is collected similarly to how it is measured in inches, with the metric system calibrated in centimeters (cm) and millimeters (mm). The collected rain is typically directed into a funnel-like device, which in turn fills a long, narrow, straight-sided cylinder with a closed bottom. The ratio of the area of the funnel's opening to the cylinder's opening is usually 5 to 1, 10 to 1, or even 50 or 100 to 1, depending on the desired accuracy.
Example Calculation
For instance, if the cylinder's inside dimension is 2 cm, the area of the opening is:
1 cm2 × 3.14 (Pi) 3.14 cm2
3.14 × 10 31.4. Divided by Pi 10, radius × 2 20 cm diameter at the top of the funnel.
If 1 cm of rain falls in the funnel, then 10 cm will collect in the cylinder. Thus, each centimeter measured in the cylinder equals 1 mm of precipitation.
Creating Your Own Rain Gauge
You can even make your own rain gauge for personal or educational purposes. Here’s how to do it:
Gather Materials
- A large diameter can without the top (e.g., a 3 lb coffee can) - A smaller tall can like a quart or liter juice can - A plastic ruler
Steps
1. Measure the diameter of the opening of the large can and calculate the area. 2. Measure the diameter of the smaller can and calculate its area. 3. Divide the large area by the small area to get the ratio. 4. Trim the end of the ruler so it is square and even with the zero mark. 5. Collect your rain in the large can. After it stops raining, pour the contents into the smaller can. 6. Stick the ruler into the smaller can all the way to the bottom and measure the water level.
Calculations
Divide the water level by your ratio to get the reading. You can use inches and 16ths or centimeters and millimeters, as long as all your calculations are consistent with your ruler.
Handling Excessive Rainfall
If you have a lot of rain in the large can and it almost fills the smaller can, measure it, write it down, then empty the smaller can. Pour the rest of the large can into the smaller can, get that measurement, and add the first measurement. Finally, divide by your ratio to get the accurate reading.
By following these steps and understanding the process of rainfall measurement, you can contribute valuable data to scientific studies and local weather reports. Happy measuring!