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| 2008/1/7-10 [Finance] UID:48901 Activity:moderate |
1/7 Does anyone know how rainfall is measured? Weather Underground
says my area got from 4-7" of rain in nearby areas, but I have a
bucket out on the middle of my driveway that filled about 15" (or
more) deep. Is it just my microclimate or is rainfall measured
differently than seems obvious? BTW, in my research I discovered
that meteorologists define temperature as that IN THE SHADE. I never
knew that.
\_ Temperature is not a well-defined quantity in sunlight.
\_ http://en.wikipedia.org/wiki/Rain_gauge
\_ How is a rain gauge different from a simple bucket? To me,
my bucket is a rain gauge is it not?
\_ Rain totals are given per 24hr period. Did you empty your
bucket daily?
\_ No, I did not. It was empty on Friday. However, I
looked up the weekly rain totals for the last two
weeks (we are already in a new week now) and they were
about 7 inches total (5.x last week and 1.x this week
so far). I looked at a lot of Personal Weather Station
data in my general area and some reported even less
than 7 inches but none anywhere near how much is in my
bucket.
\_ Did you actually stick a ruler in your bucket to
measure it? Your method should have worked, assuming
your bucket has perpendicular sides.
\_ It's a paint bucket so yes it's a big cylinder.
I measured 14 inches just now.
\_ This passage from the web page may explain OP's problem: "Also,
rain gauges only indicate rainfall in a localized area. ......"
\_ Well, duh.
\_ If you are truly curious, you should get this
http://www.scientificsales.com/Davis-6152-Wireless-Vantage-Pro2-p/6152.htm
I would, but it's a hassle convincing the wife, hehe. ;)
\_ I am thinking about getting this or something similar. It
makes me wonder how much of our weather data really applies
to us specifically. |
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| en.wikipedia.org/wiki/Rain_gauge graduated cylinders, weighing gauges, tipping bucket gauges, and simple buried pit collectors. Each type has its advantages and disadvantages for collecting rain data. hurricane can be nearly impossible and unreliable (even if the equipment survives) due to wind extremes. Also, rain gauges only indicate rainfall in a localized area. Another problem encountered is when the temperature is close to or below freezing. Rain may fall on the funnel and freeze or snow may collect in the gauge and not permit any subsequent rain to pass through. The frequency of readings will depend on the requirements of the collection agency. Some countries will supplement the paid weather observer with a network of volunteers to obtain precipitation data (and other types of weather) for sparsely populated areas. In most cases the precipitation is not retained, however some stations do submit rainfall (and snowfall) for testing, which is done to obtain levels of pollutants. Rain gauges, like most meteorological instruments, should be placed far enough away from structures and trees to ensure that any effects caused are minimised. edit Standard rain gauge The standard rain gauge, developed around the start of the 20th century, consists of a funnel attached to a graduated cylinder that fits into a larger container. If the water overflows from the graduated cylinder the outside container will catch it. So when it is measured the cylinder will be measured and then the excess will be put in another cylinder and measured. The larger container collects any rainfall amounts over 25 mm that flows from a small hole near the top of the cylinder. A metal pipe is attached to the container and can be adjusted to ensure the rain gauge is level. This pipe then fits over a metal rod that has been placed in the ground. The advantages of this type of gauge to tipping buckets is that it does not underestimate intense rain, and it can measure other forms of precipitation, including rain, hail and snow. However, these gauges are more expensive and require more maintenance than tipping bucket gauges. The weighing-type recording gauge also contains a device to measure the quantity of chemicals contained in the locations atmosphere. This is extremely helpful for scientists studying the effects of greenhouse gases released into the atmosphere and their effects on the levels of the acid rain. The interior of a tipping bucket rain gauge The interior of a tipping bucket rain gauge The tipping bucket rain gauge consists of a large copper cylinder set into the ground. At the top of the cylinder is a funnel that collects and channels the precipitation. The recorder consists of a pen mounted on an arm attached to a geared wheel that moves once with each signal sent from the collector. When the wheel turns the pen arm moves either up or down leaving a trace on the graph and at the same time making a loud click. Each jump of the arm is sometimes referred to as a 'click' in reference to the noise. The exterior of a tipping bucket rain gauge The exterior of a tipping bucket rain gauge The tipping bucket rain gauge is not as accurate as the standard rain gauge because the rainfall may stop before the lever has tipped. When the next period of rain begins it may take no more than one or two drops to tip the lever. The advantage of the tipping bucket rain gauge is that the character of the rain (light, medium or heavy) may be easily obtained. Rainfall character is decided by the total amount of rain that has fallen in a set period (usually 1 hour) and by counting the number of 'clicks' in a 10 minute period the observer can decide the character of the rain. Modern tipping rain gauges consist of a plastic collector balanced over a pivot. reed switch) which is then electronically recorded or transmitted to a remote collection station. Note that tipping gauges can incorporate weighing gauges for the best of both. In these, a strain gauge is fixed to the collection bucket so that the exact rainfall can be read at any moment. Each time the collector tips, the strain gauge (weight sensor) is re-zeroed to null out any drift. When enough water is collected to make a single drop, it drips from the bottom, falling into the laser beam path. The sensor is set at right angles to the laser so that enough light is scattered to be detected as a sudden flash of light. The flashes from these photodetectors are then read and transmitted or recorded. |
| www.scientificsales.com/Davis-6152-Wireless-Vantage-Pro2-p/6152.htm The Davis Instruments Vantage Pro2 line of weather stations retain all the great features of the original Vantage Pro line but now incorporate many additional features and improvements! The Davis Instruments 6152 Vantage Pro2 with Standard Radiation Shield transmits and receives data from up to 1,000 feet away (line-of-sight) thats more than three football fields in length! This upgraded weather station has all the features that made the original Vantage Pro so famous, yet adds many more features such as button realignment to make navigating to often-used functions much easier; a redesigned rain collector that is laser-calibrated to ensure the best accuracy possible; and a re-tooled Integrated Sensor Suite with upgraded electronics. The wireless Vantage Pro2 also has a fifth radiation shield plate to improve accuracy and readings! The Model 6152 Wireless Vantage Pro2 consists of a console unit and an innovative integrated sensor suite that includes a rain collector with self-emptying bucket, temperature and humidity sensors and an anemometer. The sensor suite is housed inside a radiation shield, protecting the sensors against solar radiation and additional sources of reflected and/or radiated heat. In addition, this high-tech Model 6152 Vantage Pro2 Wireless Weather Station will track highs and lows (and/or totals and averages) for almost all weather variables for the past 24 days, months or years and track your local forecast! With the expanded transmission range that can be extended with optional repeaters, this Model 6152 Wireless Vantage Pro2 Weather Station includes an anemometer that can be mounted with the sensor suite or detached and placed in a separate location. The Model 6152 Vantage Pro2 Weather Station from Davis Instruments includes a solar-powered sensor array and other features such as on-screen graphing, forecasting using easy-to-read icons (sunny, cloudy, rain, snow), barometric pressure trend, inside temperature, dew point, humidity information, time and date, and much more! Vantage Pro2 weather stations from Davis Instruments are the best for amateur weather observers and weather professionals alike! |