Sensor Positioning

[Big Daddy]

I would be grateful on some advice of positioning my sensors as I have limited areas around my location where they could currently go.

My current set up is that I have all the sensors attached to a 1.3m mast which sits on top of a wooden structure (used for outdoor cooking) in my garden. The structure has a sloping roof and is constructed against a 2m wall on one side which forms the back. The height of the structure is around 2m and its half boarded which means that the top half is completely open. The location of this is around 15ft from my house.

My wind sensors (speed and direction) are mounted at the top of the mast so effectively 3.3m above ground level with my temp / himidty sensor near the base of the mast, just above roof level and my rain sensor at roof level so it is held firm on the roof and doesnt wobble.

One of the problems I have is that around 10ft away there is a big oak tree which will block some of the wind when its coming in from that direction and directly behind this is my neighbours house. I have noticed that the wind direction sensor sometimes spins from west to east to west aimlessly and I dont know if this is due to the effect of the tree. I know wind doesnt blow straight but I didnt think there would be that much variation.

I could potentially mount my wind sensors on the gable end of my house and it would then be clear of any obstruction but then comes the problem of extendig wiring and having the other sensors easily accesible and in a suitable place so I can change batteries when needed and clean the rain sensor if it becomes a spider house without having to climb up on the roof.

I am also concious that I do not really want the temperature / humidity sensor in direct sunlight (I have read that somewhere) and that the rain sensor ideally needs to be fixed to avoid "tipping" with movement.

My thought on this was:
1) extend the mast by a further 1m but I dont know if this would make any difference as it still wouldnt clear the tree
2) fix the temp / humidty sensor to one of the construction supporting posts which means it would still be outside the structure but under the roof overhang therefore not in direct sunlight but still outside
3) keep the rain sensor on the roof.

I would welcome any suggestions and comments on this.............apart from chopping the tree down

Thanks

[MickinMoulden]

Extend the cable for the wind sensor. Get it as high as you can and the middle most area away from tree's (top of your house?). The tree will create wind eddies (turbulence), and most likely the reason for the wind gauge spinning around. Apart from the problem you mentioned, it will put out all you wind data, wind speed, gusts, direction, average direction, wind run. This then can effect Apparent temperature (too high), and any fire danger indexes on a website (wind speeds can be altered in the calibration section on Cumulus, there is also a recommended amount dependent on height as a guide on the wiki). Put the temp sensor out of the sun, you won't get the readings going to high because of radiating heat off the radiation shield (ironic hey), but you could pick up heat from the house. Being covered, you will suffer from night time temps not reading low enough due to it being sheltered. Best to build a radiation shield and put it out in the weather. Make sure the temp sensor won't pick up radiated heat from concrete and roofs etc. Look for the coolest place to stand during the day. Keep the rain gauge on the roof, you will get plenty saying put it just off the ground, which is great so long as there are no objects within a 45 degree elevation of it. Mine is on the roof, so that rain has a clear path to the tipper and it is very stable and level. Being level is important, this is done by making sure that each tip is done by the same amount of water. Don't rely on a spirit level on top of it. It is also important to calibrate the rain gauge, ml perfect to the area of your unit. Calibration is done then in Cumulus, and have a manual unit to back it up. Check that it has sides on your rain gauge to prevent blow out if you get windy rain. If it doesn't have sides (Fine offset don't), then build the sides up water tight. Funnels with mesh to keep spiders out works well. Photo's of your area would have helped I think.