Tuesday, April 29, 2008

Building a Weather Station

Between our co-op class focusing on meteorology, and our science class at home which is also focusing on meteorology, I think we should consider putting together our homemade weather instruments into a science fair project.  Here are the latest things we've tried.

This is a psychrometer (which is a very hard word to type!) which measures relative humidity.  It has two thermometers, one of which has the bulb wrapped in cotton cloth and the cloth is dipped into a jar of water.

After sitting out for the required hour or so, it looked like this:

We could read the difference in temperature on the two thermometers - the dry bulb was about 70 and the wet bulb was about 65, to the best of my memory now - and then use the chart that came with our handy dandy weather kit:

...to figure out the relative humidity.  Going by memory again, I think it was about 70%.

The same day, we made our first attempt at a simple homemade thermometer.  This is made with a 20 oz water bottle filled with colored water (chilled), into which we put a stopper (provided with the kit!) and a clear straw.  The trick, apparently, is to lose as little water as possible when shoving the stopper in, so that the water comes partway up that straw.

Now the challenge was - we were supposed to set it out in the sunshine, undisturbed for about an hour, then mark the water level in the straw.  (I took this picture before marking the starting water level, which turned out to be a good thing...)  Then we were to put it in the shade for an hour and mark the level again.  Both times we would also check the actual temperature on a traditional thermometer, and that was supposed to help us calibrate our thermometer.  Well... as I said... the challenge  - we live in a wind tunnel, I think.  Our poor bottle kept tipping over in the wind, no matter where I put it (not a lot of options either, since it was supposed to be in the sun!) and of course, each time we would have to refill and get that stopper on again.  Frustrating.   So we gave up around 4pm as the sun was getting too low for this to really be effective. 

We decided we would try it again on the next sunny day.

Which at this point, I think might happen sometime in June...

This was the creek near our house within a couple of days after our aborted thermometer experiment:

Yeah, pretty high.  Lots of rain here lately, and usually on baseball days too.  So what we SHOULD have done, was put out our homemade rain gauge and calibrated THAT.  Oh well.

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short said...

for you to come and live here where we have lots of sun - even in winter!

We have all had a good lesson reading your blog, and looking at the photos - thanks :-)

msack said...

We need to try some of this. I am planning a summer unit on weather now. (Scince got left behind some this year) Where did you get all of your project ideas?

Anonymous said...

Now that was a cool entry! I didn't even know that piece of equipment existed. I thought you'd put together a weather station that basically did temperature, rainfall, and maybe wind speed. Your station goes above and beyond...nice job!

MayTheyBeMightyMen said...


I am not anonymous! *lol*

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