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Shelter from the Storm: Remote Thermometer Housing

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I don't much care for going outside to find out how cold or hot it is. It's no good me calling the time-and-temperature phone number, either, as I live 30 miles from town and at a higher altitude. With that in mind I picked up a wireless remote thermometer at Big Lots for $10 or so. I then needed a good place to mount the remote sensor. Thermometers exposed to the sky will read much too high in the sun and too low when exposed to a clear night sky. Being too close to a building can affect the temperature reading as well. So I decided to build myself a small, simple version of what's known as a Stevenson screen or cotton region shelter. This is what I came up with. So far it seems to be working well.


 
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Step 1: Location

Picture of Location

First a note on locating the shelter for the most accurate readings: The National Weather Service (NWS) advises that your sheltered thermometer should be
-between 4' to 6' above fairly level ground
-which is typical for your area (sand with a little grass here),
-has good cross-ventilation,
-and which is located 100' or more from concrete or asphalt paving
-and at a distance from the nearest building equal to four times the height of the building. As my house is about 12 feet high, I needed to put the post about 50' from the house. The advertised range for my thermometer is 100', but if you've got a cheap thermometer as I do, I would leave a wide margin for error (i.e. no more than 60' or so).

Now if you live on a small lot in town, you are looking at this and thinking "no way!" This is true if you want to supply data to the NWS. On the other hand, if you just want to know what the temperature is, say, out in your garden, put your shelter there and don't worry too much about it.

gwylan (author) 2 years ago
As of today I have added a floor to the housing, and put notes and a couple of photos in step 7 for those who might need one.

The floor is (thin) aluminum also. While other materials are commonly used--i.e. wood and plastics--the aluminum is easy to work with and appears to be doing a dandy job so far. I'd be interested in seeing what other folks come up with, however.
gwylan (author) 3 years ago
Several responses:

Some web searching assures me that aluminum has been used for 'official' (as opposed to homebrew) Stevenson shelters--unshaded, at that. Whether those shelters work well is another matter.

The aluminum I'm using is very thin (little mass) and very reflective, so if I remember my physics correctly, it should reflect more heat than it will radiate.

Overall results so far show that the outdoor temperature readout, even on an absolutely clear day, is just about right (i.e. is comparable to my shaded porch). With one exception! Yesterday afternoon was both sunny and still--unusual in this season--and the temperature readout seemed a bit high. I am going to keep an eye on this for awhile longer. If necessary, I'll find a larger piece of roofing. It will, at least, be very easy to replace--make four holes for the bolts and then just swap it out for the current roof.

While I am still unsure of the necessity of more shade, one thing is certain: more shade can't hurt.
85rocco gwylan2 years ago
I've seen quite a few different screen designs so I don't think there's an international standard for these things but in Canada where I am, the official Stevenson screens used by Environment Canada approved sites are made out of wood painted a flat white inside and out. They're quite large, they sometimes have a blower mounted on top which draws fresh air over the thermometers and sensors.

Anyways, I like what you've done, just paint the whole thing in a flat white. Believe it of not, white is more heat reflective than shiny aluminium, if you doubt that, take two pieces of shiny aluminium, paint one white, put them out in the sun and the white one will remain noticeably cooler to the touch.
gwylan (author)  85rocco2 years ago
As you say, there are a lot of different designs.

After weeks of tracking the results from my shelter, I've been pleased with the results. On sunny, still days it sometimes reads a little high (1 degree or less, a figure arrived at by shading the shelter completely). I lessened that gap--believe it or not--by closing in the bottom of the shelter with more thin, reflective material (a couple pieces of a foil dog food bag taped into place, though I'll replace that soon). This works because heat is being reflected upwards from the sand. If the shelter was located over grass, I don't think that would be a problem.
85rocco gwylan2 years ago
You're quite right about heat reflected from the sand,. It's best to have these things mounted in the middle of a large chunk of lawn away from buildings, roads, parking lots etc. Of course, that's not always possible so one does the best they can with the site they've got and it sounds like you're getting a handle on that.
St Jimmy gwylan3 years ago
Possibly paint the inside of the aluminium black, so that it reflects as much outside heat as possible and absorbs any heat inside the stevenson's screen, although I'm not sure whether this would just encourage more insolation than before
gwylan (author)  St Jimmy3 years ago
This is one of the things I'm considering. I don't know if it would make much difference, but I don't think it would hurt.
ARJOON3 years ago
by reading the title i thought that this pole was meant for humans to take shelter in there during storms
SandLizard3 years ago
I live in the Arizona desert and in the summer I can put my hand against the inside of the wall in my house and feel the heat from the sun shining on the outside wall, even with the insulation. Air conditioners work better when shaded here, evaporative coolers cool the inside of a house about 5 degrees cooler when shaded. I think doing something to keep the metal shaded would be a big difference here in the summer.
mcegans3 years ago
I used to work at an airport that did weather monitoring. They used a box similar to this only it was wood. It was also painted white to prevent heat absorption, it had a small muffin type fan in it for circulation
rkbrumbelow3 years ago
I don't know where you live, but putting a thermometer in anything coated with metal where I live is akin to putting it in an oven.
The key is not the heating of the metal but the air circulation. This design works.
There would have to be a LOT of air circulation. Even with good circulation the metal is going to heat up and cause radiant heat transmission. This is the reason Stevenson screens were originally made of asbestos and are now made of laminate. Remember they also have to regularly be repainted.
gwylan (author)  rkbrumbelow3 years ago
New Mexico. Pretty fierce sun here. So far, the daytime highs registered in the shelter have been pretty much in line with regional norms. Midsummer may be a different story, but I don't think so. The metal is highly reflective and allows for good air circulation.
dchall8 gwylan3 years ago
A mirror is highly reflective, too, but if you leave it out in the sun you can cook on it. In my opinion you need to completely shade the finned metal to get an accurate temp. Or you could use a white, plastic finned material.

I used to work in a medical research organization where they were studying the effect on firefighters of putting out airplane fires in Saudi Arabia.  Firefighters wear heavy, flame protective clothing in conditions of unbearable ambient heat along with the heat of kerosene burning.  A human can only perform so much hard work in those conditions.  In order to do the research they had to know all they could about the heat.  They used a box similar to yours but with a broader cover on top to shade the 'can' underneath.  Inside they had ambient and water soaked thermometers to measure heat and humidity.  They also had a thermometer mounted inside a black, brass ball (they used a painted toilet float).  The reason for that was to measure cloud cover.  On a cloudy day, the 'black globe' temperature was the same as the ambient temperature.  That is important because on a cloudy day the firefighter would not be absorbing radiant heat from the sun.  Interesting project. 
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