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jlhredshift
2010-Sep-07, 07:09 PM
I just bought a new weather station and I am pondering where to put it. It is a wireless unit with a thousand foot range. Besides the house we have two out buildings, a barn and a 24x30 garage, neither of which is shaded. The property is bounded on the north by second growth mature forest. The wind sensor remote is separate from the temperature/humidity unit, which is why I liked this station. I am considering putting the wind unit on the peek of the barn, but the temperature unit I am unsure as to the best location because any of the buildings emit infrared, I have a viewer/scope, even on the north side.

Suggestions?

Canis Lupus
2010-Sep-07, 09:15 PM
Put it in the middle of km's of concrete, just next to an air conditioning vent. This is a perfectly acceptable location to place weather stations to gauge accurate world temperatures.

Swift
2010-Sep-07, 09:26 PM
Put it in the middle of km's of concrete, just next to an air conditioning vent. This is a perfectly acceptable location to place weather stations to gauge accurate world temperatures.
Canis Lupus,

You are not fooling anyone with that comment. If you want to make jokes about global warming, stick in a :D. If you want to advocate a non-mainstream position about temperature data and global warming, do it in ATM.

jlhredshift
2010-Sep-07, 09:41 PM
I thought about building a simple covered shelf and placing it far enough into the trees to the north to avoid the heat coming off the white rock driveway but then I'm measuring the forest temp which is always cooler than the front yard. I feel a compromise coming on.

jlhredshift
2010-Sep-07, 10:26 PM
While we're thinking on the temp thing, another question, I am more interested in the absolute air pressure at my location, therefore I think that means that I leave the altitude set to zero; correct?

Ivan Viehoff
2010-Sep-15, 03:49 PM
I have a very basic weather station answering to the description you make, though I think mine was described as having only about 100ft radio connection. (Though it works perfectly despite there being a double glazed window, the corner of a brick built building and all of a wooden building between it and the receiver.)

As soon as you get any direct incident sun on the temperature sensor, it goes wild. I put mine in a very narrow gap between the north wall of a wooden shed and an evergreen hedge, but, like satellite television sun-outs, it gets incident sun on it for a few hours per year. I would also observe that I record temperatures a couple of degrees centigrade above met-office readings on very warm sunny days, as incidentally do other local web-connected amateur weather stations, one in particular of which is using some pretty good kit. Rather than taking this as confirmation of the higher temperature of our location than the met office location, I take it as confirmation of how difficult it is to get a sun-unaffected temperature reading in conditions of high incident solar radiation. As you say, the temperature in the yard is higher than in the wood. But what are you interested in? The temperature in the wood, on all but the calmest of days, is closest to the true air temperature for climatic purposes. If you want to know the temperature in the yard, then measure the temperature in the yard. But then you will have difficulty understanding what "the temperature in the yard" means because I expect it will vary considerably depending upon how high above the pavement you are.

Measuring wind is difficult. Wind is a very local phenomenon, affected by topography, buildings, trees, etc. You need to get up above all local vegetation and buildings, and even then you are at risk of having local channelling towards or away from your sensor. My wind sensor never worked properly. At first I thought it was just because I had it so low down - only had it about 3m above the ground, whereas professional ones would be at 10-20m. But after a while it stopped working altogether, so actually I don't think it was ever working properly. I'm somewhat suspicious of the rain measurement during heavy rainfall also. But the sensors and radio connection have so far worked continuously for 18 months without changing the AA batteries, which is quite amazing. When you consider I only paid about GBP 100 for the whole lot, and next level starts taking you into GBP500 territory, I think I got what I paid for. The other disadvantage of mine, which I didn't understand until I'd got it, is that the only way of logging the data from it is to have a computer permanently switched on and connected to it, as its output is not compatible with available dataloggers. I had misread the specs and thought it had built in data-storage one could download from time to time. But one with built-in or add-on dataloggers would be much more expensive. You'd think they'd have ones you could plug in a USB data stick to log data these days.

jlhredshift
2010-Sep-16, 01:51 AM
Ivan, you raise an interesting question that changes how I was thinking about the problem of air temperature and it actually relates to what you have said in reference to wind variability. I see now that I wanted to avoid "temperature channeling". I mean for instance, that the rock of the driveway re-radiates heat at the end of the day so I wanted to avoid that effect on the temp guage, same with the buildings. As you have pointed out with the sun issue, that needs to be avoided as well because it kills the reading accuracy. I guess that what I am really after is to avoid the micro climates seeking to best measure the average temp of the farm without these islands of interference, or, as they would say, noise. I see now the same is true with the wind, so I think I am going to mount the wind guage on a post well above the barn, which the peek is the highest point, to avoid as much turbulence as possible. The rain guage I think I will put on one of the larger and taller, and more stable, fence posts next to the pasture but above where the animals could chew on it. No data logger on this one either.

Edit to add: In regards to the rain guage, spiders and bird poo may be an issue.

Ivan Viehoff
2010-Sep-16, 10:48 AM
I once heard a radio interview with the farmer who has the weather station which is described as the wettest inhabited location in Britain, a hamlet called Seathwaite in Cumbria - the one in Borrowdale south of Keswick, not the other one. It turns out that he has two identical rain gauges on his farm about 200 yards apart. One consistently records about 10-20% less rainfall than the other one, even when he swaps them around to test whether it is the instruments. The farm is in a valley, and the more westerly rain gauge, ie the one that is more in the lee of the valley bank in relation to the prevailing wind, is the drier one. Microclimates can be very micro when you have significant topography. Even without topography, large local variations can occur. In August I suffered two substantial downpours, which were rougly 20mm and 25mm (that's a downpour in Britain), whereas the good quality amateur weather station about 4-5 miles away missed one completely and only got 10mm from the other. On other occasions, I've had no rain when they've had downpours there. Since we both lie on essentially the same part of the Chiltern plateau, I would expect our weather to be very similar. Last winter, a town a similar distance in the other direction was the coldest town in Britain one night, with a recorded minimum of -12C. It lies in a valley, ie a frost pocket. Up on the plateau above it (the valley is only 60m deep), I recorded a minimum of -8C that night. But it shows how variable weather can be from one location to another. I think one would need a large number of weather stations to be reasonably sure one was getting a representative average.

jlhredshift
2010-Sep-16, 12:22 PM
Ivan,

That is correct and I am trying to think this thing through so as to avoid obvious micro micro issues knowing the best I can do is not be totally dumb in the placement.

We live a little more than a mile south of Lake Erie and I have watched storms coming out of the north northwest go around me but dump substantial rain to the east and west, which irritates me in July and August when the pastures need rain. If the line of storms comes out of the west we usually get the same rainfall as everyone else. I assume it is because of the rising topography of the lake shore north of us. However, the benefit of that feature is that during the winter we will get no or a little snow while those south of us will get buried, or as it is called, those in the snow belt.