Comments on: What can we make lots of little Stevenson Screens out of?

Question: What can we make lots of little Stevenson Screens out of?

Jimbob — Thu, 13 Sep 2007 18:55:06 -0800

Handy people: What's a good way to make lots of small, Stevenson Screen type things on the cheap and easy?

For an experiment we're conducting outdoors, we have a whole bunch of little iButton temperature and humidity sensors (about the size of a computer-clock battery). We don't want to just stick them on our experimental plots, because they would be affected by direct sunlight and wind. In weather recording, Stevenson screens are used to shade sensors from direct sunlight and strong wind, while still allowing a flow of ambient air around the sensors. Alas, "proper" Stevenson screens are expensive, or quite complicated to construct (as per my link above), particularly when you need 65 of them.

Do any people with a better knowledge of gadgets and hardware than I have any ideas of how we could make lots of little shelters to protect our sensors in a similar way? Items that could be modified to shade and reduce wind effects around our little sensors? Something that could be re-purposed?

By: Quietgal

Quietgal — Thu, 13 Sep 2007 19:20:59 -0800

Empty yogurt or cottage cheese containers? Cut some vents in the sides and invert over your sensors.

you didn't say you needed elegant

By: DMan

DMan — Thu, 13 Sep 2007 19:21:11 -0800

A question: How long do these need to last? And are you concerned about things like rain?

Right now the best thing I can come up with is small plastic cups with a few small holes drilled in them to allow air to get in.

By: chef_boyardee

chef_boyardee — Thu, 13 Sep 2007 19:23:53 -0800

I think these things are big for a reason, as otherwise you start picking up heat sink effects from the screen hardware.

By: Jimbob

Jimbob — Thu, 13 Sep 2007 20:19:11 -0800

They need to last about two weeks out in the open; the idea of cups of yoghurt containers are pretty good, I might see how well they work. Chef, you raise a good point - I can see the point of them being large...unfortunately in the environment in which we're working, the larger these things are, the more likely they are to impact on the micro-environment of the organisms we're watching.

By: dg

dg — Thu, 13 Sep 2007 20:46:48 -0800

What about cheap lampshades of some sort (a trip to Bunnings would surely turn something up) - they also would have some form of mounting point you could adapt.

Could you surround them with stakes and shade cloth, or do they need to be off the ground?

Icecream containers are perhaps large enough to avoid any heat sink effects without being big enough to affect your experiment. Plus, you get to eat a shit load of icecream.

Companies who provide teaching materials to pre-schools often have all sorts of containers that may be of use.

By: Jimbob

Jimbob — Thu, 13 Sep 2007 21:26:52 -0800

Yeah icecream containers sound like a better idea than the smaller yoghurt containers, actually - more space, and sturdier plastic.

We are actually planning on putting these things on a stake (the experiment is on mosquito breeding in a swamp, so we need to keep things off the ground to stop them getting wet).

By: dg

dg — Thu, 13 Sep 2007 21:35:03 -0800

Then you could put a cross-piece on the stake the same length as the width of the container and screw through the sides of the upside-down container into the cross-piece to hold it in place, with the sensor on the top of the stake.

Should I bring my own spoon to help with emptying out the containers?

By: Mitheral

Mitheral — Thu, 13 Sep 2007 21:40:12 -0800

That's a swack load of ice cream. You can get mixing cups in assorted sizes and materials at most auto body supply places.

By: Womanscientist

Womanscientist — Fri, 14 Sep 2007 03:14:11 -0800

My field site is in a salt marsh, and all of my supplies (except for the in-situ instruments) are purchased at hardware stores.....I like the mixing cup idea, too. Even small paint buckets people use for 'cutting in' would probably work just fine.

By: scruss

scruss — Fri, 14 Sep 2007 08:22:32 -0800

R M Young 41003 radiation shields are not that expensive (though more expensive than your iButtons, for sure). They do have a well-defined radiation error, though, which your J. Random PlasticCup may not.