Instructions

Instructions for Rain Gage Volunteers

12/18/2002

PURPOSE: To create a data bank of precipitation information for your local area that can be used for future reference by anyone who might need that type of information in your general area.

WHERE: You should place your rain gage in an open area, away from tall obstructions, if possible. If you do not have a wide-open area for your gage, try to place the gage such that any obstructions are to the northeast, east or southeast of your gage. Make sure that the top of the gage sits high enough above any support, so that the rainfall catch is not affected by splash against the support. One of the best locations for a gage is on the north side of a fence, as the lower part of the gage will usually be shaded, and be less prone to evaporation loss during the summertime.

WHEN: In order to standardize your data, you should record a daily precipitation total at about the same time each day ? a time that is convenient for you on weekdays and weekends. If you cannot read your gage at your normal observation time on any given day, it is OK to read it at a different time ... just make a note of the actual reading time on your daily log. Whenever you read the gage, always write down the amount, and empty the contents of the gage to make sure that it has plenty of capacity for the next storm event.

HOW: Once you become a volunteer, you may purchase your own gage, or one can be provided to you. You will also be provided with a standard form on which you can record your daily precipitation amounts. Feel free, though, to use any method of recording your data that is most convenient for you (such as on a calendar or in a daily planner book). If you decide to use the special CORN form, there is an electronic version (Excel) of this form available for keeping your data on a computer ... it will automatically add your monthly total as you go.

A filled out sample of one of our data forms is included with these instructions to illustrate some of the basic techniques used when recording your data. It is a fictitious report for John Doe, and covers the month of June 2000. Note that he has elected to read his gage at 6 p.m each day. His reading of 1.10 inches on June 23 tells us that 1.10 inches of precipitation fell sometime between 6 p.m on June 22 and 6 p.m. on June 23, although we don't know exactly when it fell or how long it lasted during that 24-hour period. It is most important to understand that the amount that you record on a given date at your observation time represents the amount of precipitation that has fallen in the 24-hour period previous to your observation time on that date.

There will be times when you may not be able to record your daily reading. Note on the sample report, that on June 10, 11 and 12, the symbol * is used. This symbol is used to indicate that the gage was not read on those days, but that an accumulated total of precipitation is made on a later date. On this sample sheet, the total of 1.75 inches on June 13 represents the total precipitation that fell during June 10-13. Although it may seem to you that a 4-day total of precipitation has little value, it really is important to record accumulated totals if you can, because we are also interested in monthly and annual rainfall totals at our gage locations. If you should happen to miss a daily reading where you know that there was precipitation, but it evaporated before you had a chance to read your gage, enter the symbol "M" for "Missed reading" ... may be possible to estimate a daily total for you, based on data from nearby gages. If you have some very light precipitation on a given day that is not measurable in your gage, use the symbol "T" for a "trace" of precipitation.

Beginning on the 1st of each month, data is collected from our volunteers for the previous month by Bob Davis. There are a number of ways that you can turn in your data ... the various options are shown in the table below. Your data will be combined with data from other volunteers into a monthly Central Ohio Raingage Network (CORN) report. You will receive a free copy of each monthly report once you become a volunteer raingage reader with CORN.

Method of Communication At the Office (EMH&T, Inc.) At Home: By regular mail: EMH&T, Inc. 170 Mill Street Gahanna, OH 43230 Mr. Robert C. Davis 260 Glenmont Ave. Columbus, OH 43214 By phone: To EMH&T, Inc. front desk: (614) 471-5150 Direct line to Bob Davis: (614) 470-9455 (614) 261-4667 By fax: To EMH&T, Inc. main building: (614) 471-9286 Directly to Bob Davis computer: (614) 470-9578 - By e-mail: Directly to Bob Davis computer: bdavis@emht.com To home computer: therainguy@yahoo.com

FREQUENTLY ASKED QUESTIONS (FAQ?s) and ANSWERS:

Q: Should I empty my gage after I read it, or should I let the water accumulate?

A: You should always empty your gage after you take your reading, to minimize the chances of the gage filling up or overflowing with the next storm. Also, if you leave the water in the gage, some unknown portion of it is likely to evaporate before the next storm.

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Q: How do I measure precipitation in the wintertime?

A: I always show the melted equivalent of any snowfall in the daily amounts shown in our reports. When you collect snowfall in your gage, the best methods of obtaining the melted equivalent of that snowfall are as follows:(1) take the gage indoors after the storm is over and let the precipitation melt, then read the water equivalent in the gage; (2) purchase a second gage, and rotate the gages using Method #1, so that there is always a gage outside ready to catch precipitation; (3) add a known volume of warm water to your gage to melt the frozen contents ... the melted equivalent is then equal to the difference between the total melted mixture and the known volume of water added to the gage; or (4) try to estimate the amount of snow that actually fell, by averaging the snowfall depths at about 2 or 3 representative locations in your yard to the nearest ? or ? inch, if possible ... then mark the snowfall amounton your sheet, making sure to indicate that it is a snowfall amount, and then let me estimate the melted equivalent. I will typically make the conversion from snowfall amount to melted equivalent based on the published ratio from Port Columbus for that given storm.

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Q: When water accumulates in my gage, the top of the water surface appears curved. How do I read the amount of precipitation for my daily reading?

A: The curved surface is called a meniscus, and it is caused by the attraction of the water droplets to accumulated dust and dirt inside your gage. The effect can be minimized by giving the inside of your gage an occasional cleaning with soap and water. Take your reading as an average between the top and bottom of the meniscus.

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Q: How do I account for precipitation in my gage if I go on vacation, or I cannot make any readings for several days?

A: Obviously, any rain that falls in your gage will be subject to evaporation loss while you're gone. If you are not able to get a friend or neighbor to read your gage while you are gone, before you leave, put a known quantity of water (0.5 or 1.0 inch) in your gage. This volume of water will evaporate slowly, and any added precipitation should not evaporate quickly while you are gone. Just remember to subtract the amount of water that you put in your gage before you left when you return and record your accumulated total!!

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Q: I normally read my gage at 6 p.m., but there were a couple of days when I forgot, and read my gage at a different time. How should I record my data?

A: There will be times when it is not possible to make your reading at your normal reading time (plus or minus 15 minutes). In this case, just make a note of what time you read your gage on your data sheet, and pass that information along when you turn in your daily totals at the end of the month. (Keep in mind that if you normally read your gage at 6 p.m., but read it at say, 9 p.m., and you know that it didn't rain between 6 p.m. and 9 p.m., you can still consider your 9 p.m. reading to be a 6 p.m. reading).

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Q: My rain gage has two different scales on it. Which one should I use?

A: Our monthly CORN report presents rainfall amounts in inches, so you should try to record your data in inches. The inches scale on your gage will be the one that has an upper value of approximately 5 to 6 on it. If you do make a reading using the other (metric) scale, be sure that you indicate that your reading is a metric reading on your data sheet.

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Q: I have an automatic sprinkler system, or I occasionally water my lawn. Will this affect my daily precipitation readings?

A: If your rain gage is located in an area that your sprinkler can reach, your data could very well be affected by the water from your sprinkler. Make sure that you either remove your gage while you are watering, or better yet, place your gage in a location that will not catch the water from your sprinkler.

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Q: How do I read the rainfall amount if the water level in the gage goes above the highest recording mark (for most volunteers, 5.5?) on my gage?

A: This may seem like an unlikely possibility, but it actually happened to some of our Grove City area volunteers during a storm on June 29, 1998. If this happens to you, I recommend the following procedure: (1) First, somehow mark the top level of the water on the outside of your gage, so that you can re-create Steps 2-4 in case something goes wrong; (2) Take the gage indoors and pour a portion of the contents of your gage into a second container, such as a measuring cup ... then read the amount left in the gage, write the amount down, and empty the amount you just read; (3) Now pour the contents from the second container into the gage, read that amount in the gage, and write that amount down; (4) The last step is to add the two (written-down) readings together to get your total rainfall amount.

Month: June Gage Station # 176

Year: 2001 Reader: John Doe

Time of Observation: 6:00 p.m.

Day Precipitation (inches) Comments

4 0.1

9 0.35

10 *

11 *

12 *

13 1.75

17 T

23 1.1

Total 3.30


	Instructions for Rain Gage Volunteers 12/18/2002
		PURPOSE: To create a data bank of precipitation information for your local area that can be used for future reference by anyone who might need that type of information in your general area. WHERE: You should place your rain gage in an open area, away from tall obstructions, if possible. If you do not have a wide-open area for your gage, try to place the gage such that any obstructions are to the northeast, east or southeast of your gage. Make sure that the top of the gage sits high enough above any support, so that the rainfall catch is not affected by splash against the support. One of the best locations for a gage is on the north side of a fence, as the lower part of the gage will usually be shaded, and be less prone to evaporation loss during the summertime. WHEN: In order to standardize your data, you should record a daily precipitation total at about the same time each day ? a time that is convenient for you on weekdays and weekends. If you cannot read your gage at your normal observation time on any given day, it is OK to read it at a different time ... just make a note of the actual reading time on your daily log. Whenever you read the gage, always write down the amount, and empty the contents of the gage to make sure that it has plenty of capacity for the next storm event. HOW: Once you become a volunteer, you may purchase your own gage, or one can be provided to you. You will also be provided with a standard form on which you can record your daily precipitation amounts. Feel free, though, to use any method of recording your data that is most convenient for you (such as on a calendar or in a daily planner book). If you decide to use the special CORN form, there is an electronic version (Excel) of this form available for keeping your data on a computer ... it will automatically add your monthly total as you go. A filled out sample of one of our data forms is included with these instructions to illustrate some of the basic techniques used when recording your data. It is a fictitious report for John Doe, and covers the month of June 2000. Note that he has elected to read his gage at 6 p.m each day. His reading of 1.10 inches on June 23 tells us that 1.10 inches of precipitation fell sometime between 6 p.m on June 22 and 6 p.m. on June 23, although we don't know exactly when it fell or how long it lasted during that 24-hour period. It is most important to understand that the amount that you record on a given date at your observation time represents the amount of precipitation that has fallen in the 24-hour period previous to your observation time on that date. There will be times when you may not be able to record your daily reading. Note on the sample report, that on June 10, 11 and 12, the symbol * is used. This symbol is used to indicate that the gage was not read on those days, but that an accumulated total of precipitation is made on a later date. On this sample sheet, the total of 1.75 inches on June 13 represents the total precipitation that fell during June 10-13. Although it may seem to you that a 4-day total of precipitation has little value, it really is important to record accumulated totals if you can, because we are also interested in monthly and annual rainfall totals at our gage locations. If you should happen to miss a daily reading where you know that there was precipitation, but it evaporated before you had a chance to read your gage, enter the symbol "M" for "Missed reading" ... may be possible to estimate a daily total for you, based on data from nearby gages. If you have some very light precipitation on a given day that is not measurable in your gage, use the symbol "T" for a "trace" of precipitation. Beginning on the 1st of each month, data is collected from our volunteers for the previous month by Bob Davis. There are a number of ways that you can turn in your data ... the various options are shown in the table below. Your data will be combined with data from other volunteers into a monthly Central Ohio Raingage Network (CORN) report. You will receive a free copy of each monthly report once you become a volunteer raingage reader with CORN. Method of Communication At the Office (EMH&T, Inc.) At Home: By regular mail: EMH&T, Inc. 170 Mill Street Gahanna, OH 43230 Mr. Robert C. Davis 260 Glenmont Ave. Columbus, OH 43214 By phone: To EMH&T, Inc. front desk: (614) 471-5150 Direct line to Bob Davis: (614) 470-9455 (614) 261-4667 By fax: To EMH&T, Inc. main building: (614) 471-9286 Directly to Bob Davis computer: (614) 470-9578 - By e-mail: Directly to Bob Davis computer: bdavis@emht.com To home computer: therainguy@yahoo.com FREQUENTLY ASKED QUESTIONS (FAQ?s) and ANSWERS: Q: Should I empty my gage after I read it, or should I let the water accumulate? A: You should always empty your gage after you take your reading, to minimize the chances of the gage filling up or overflowing with the next storm. Also, if you leave the water in the gage, some unknown portion of it is likely to evaporate before the next storm. ------------------------------------------------------------------------------------------------------------ Q: How do I measure precipitation in the wintertime? A: I always show the melted equivalent of any snowfall in the daily amounts shown in our reports. When you collect snowfall in your gage, the best methods of obtaining the melted equivalent of that snowfall are as follows:(1) take the gage indoors after the storm is over and let the precipitation melt, then read the water equivalent in the gage; (2) purchase a second gage, and rotate the gages using Method #1, so that there is always a gage outside ready to catch precipitation; (3) add a known volume of warm water to your gage to melt the frozen contents ... the melted equivalent is then equal to the difference between the total melted mixture and the known volume of water added to the gage; or (4) try to estimate the amount of snow that actually fell, by averaging the snowfall depths at about 2 or 3 representative locations in your yard to the nearest ? or ? inch, if possible ... then mark the snowfall amounton your sheet, making sure to indicate that it is a snowfall amount, and then let me estimate the melted equivalent. I will typically make the conversion from snowfall amount to melted equivalent based on the published ratio from Port Columbus for that given storm. ------------------------------------------------------------------------------------------------------------ Q: When water accumulates in my gage, the top of the water surface appears curved. How do I read the amount of precipitation for my daily reading? A: The curved surface is called a meniscus, and it is caused by the attraction of the water droplets to accumulated dust and dirt inside your gage. The effect can be minimized by giving the inside of your gage an occasional cleaning with soap and water. Take your reading as an average between the top and bottom of the meniscus. ------------------------------------------------------------------------------------------------------------ Q: How do I account for precipitation in my gage if I go on vacation, or I cannot make any readings for several days? A: Obviously, any rain that falls in your gage will be subject to evaporation loss while you're gone. If you are not able to get a friend or neighbor to read your gage while you are gone, before you leave, put a known quantity of water (0.5 or 1.0 inch) in your gage. This volume of water will evaporate slowly, and any added precipitation should not evaporate quickly while you are gone. Just remember to subtract the amount of water that you put in your gage before you left when you return and record your accumulated total!! ------------------------------------------------------------------------------------------------------------ Q: I normally read my gage at 6 p.m., but there were a couple of days when I forgot, and read my gage at a different time. How should I record my data? A: There will be times when it is not possible to make your reading at your normal reading time (plus or minus 15 minutes). In this case, just make a note of what time you read your gage on your data sheet, and pass that information along when you turn in your daily totals at the end of the month. (Keep in mind that if you normally read your gage at 6 p.m., but read it at say, 9 p.m., and you know that it didn't rain between 6 p.m. and 9 p.m., you can still consider your 9 p.m. reading to be a 6 p.m. reading). ------------------------------------------------------------------------------------------------------------ Q: My rain gage has two different scales on it. Which one should I use? A: Our monthly CORN report presents rainfall amounts in inches, so you should try to record your data in inches. The inches scale on your gage will be the one that has an upper value of approximately 5 to 6 on it. If you do make a reading using the other (metric) scale, be sure that you indicate that your reading is a metric reading on your data sheet. ------------------------------------------------------------------------------------------------------------ Q: I have an automatic sprinkler system, or I occasionally water my lawn. Will this affect my daily precipitation readings? A: If your rain gage is located in an area that your sprinkler can reach, your data could very well be affected by the water from your sprinkler. Make sure that you either remove your gage while you are watering, or better yet, place your gage in a location that will not catch the water from your sprinkler. ----------------------------------------------------------------------------------------------------------- Q: How do I read the rainfall amount if the water level in the gage goes above the highest recording mark (for most volunteers, 5.5?) on my gage? A: This may seem like an unlikely possibility, but it actually happened to some of our Grove City area volunteers during a storm on June 29, 1998. If this happens to you, I recommend the following procedure: (1) First, somehow mark the top level of the water on the outside of your gage, so that you can re-create Steps 2-4 in case something goes wrong; (2) Take the gage indoors and pour a portion of the contents of your gage into a second container, such as a measuring cup ... then read the amount left in the gage, write the amount down, and empty the amount you just read; (3) Now pour the contents from the second container into the gage, read that amount in the gage, and write that amount down; (4) The last step is to add the two (written-down) readings together to get your total rainfall amount. Month: June Gage Station # 176 Year: 2001 Reader: John Doe Time of Observation: 6:00 p.m. Day Precipitation (inches) Comments 1 2 3 4 0.1 5 6 7 8 9 0.35 10 * 11 * 12 * 13 1.75 14 15 16 17 T 18 19 20 21 22 23 1.1 24 25 26 27 28 29 30 31 Total 3.30