Tuesday, November 3, 2015

Yet Another Failed Experiment: Land and Sea Breezes


I am so sorry that I didn't move the jars of dog food before I took this picture.  Gross.  But yes, this is my life since we got a dog.  One of the presentations I gave the boys in the past few weeks was on land and sea breezes.  My record on Montessori geography demonstrations now stands at 3-4.  Another experiment failed.  I don't know how I messed this one up.  (You can read about how I failed at "air takes up space" here, warm air rises here, and radiant heat here. )  You can read about how to do this presentation in your albums, or otherwise the activity and information here is quite comparable, and I like the follow-up questions suggested.  Basically I put equal amounts of sand and water each into their own pie tin.  We recorded the temperature of each at the start, then after heating it on the stovetop for three minutes, and again after cooling them outdoors (it was cold outside) for ten minutes.


Any experiment that asks me to heat more than one thing on a burner at the same time for the purposes of comparison instantly flummoxes me because of how our burners are designed.  All five of my burners are different sizes and have one of two different BTU's.  There is no way for me to heat two things simultaneously but equally except placing two identical containers equally spaced over the one large elliptical burner.  While this won't get me published in a peer-reviewed scientific journal, I believe this solution should be equal enough for the types of things we are doing at  home to date as long as the each vessel doesn't need to be heated uniformly.  They are both heated nearly equally here, but also heated equally lopsided.  

In the demonstration the land (sand) is supposed to heat AND cool faster than the water.  Our land heated marginally faster (two degrees?) but both the sand and water cooled exactly ten degrees during their ten minutes outside.  My only hypothesis is that I didn't use enough sand and water. If I had used a larger amount of both sand and water perhaps I would have gotten a bigger difference when heating.  Likewise, if the amount of sand and water I used wasn't enough perhaps the ten minutes outside was too long and the water reached a point where the cooling slowed drastically and then the sand caught up.

Anyway, I discussed this with the boys and we proceeded as if all had gone according to plan.



We talked about how these different rates of heating and cooling would create a sea breezes and land breezes.  




On a different day I presented "Changes in the Winds Caused by Seasons."  The KotU album wisely has five charts for this.  The first two charts show how temperatures change in accordance with whether the perpendicular rays of the sun are falling at the Tropic of Cancer or Tropic of Capricorn.  The areas of land on the Earth are color coded by temperature.  Here is an example:



The third chart is the same picture, with all of the land now in brown and the direction of variable and steady winds are added.  The fourth and fifth charts combine the wind arrows with color-coded land again, but this time the color coding reflects the amount of precipitation rather than the temperature. There is one chart for when the perpendicular rays of the sun fall at the Tropic of Cancer and another for the Tropic of Capricorn.  My friend Abbie posted about this lesson and has lots of good pictures of the charts.  Rather than repost the same here, I will refer you to her excellent post.    

The ETC charts only provide the final two charts.  Following closely on the heels of the sand and water demonstration, the boys jumped to the conclusion that the color coding referred to the temperature and that the blue areas were cold.  On those charts, the blue actually refers to rainy and those areas are hot not cold.  I always have Jessica's charts at least on the iPad if not printed so I was quickly able to dig us out of that confusing situation.  The five charts rather than the two are definitely necessary here not only to avoid confusion but also because you can lay the temperature and precipitations charts side by side and make some nice observations.  The KotU course provides printable images for all of the charts in this album.  That was a really nice feature.  I was able to show them the other charts on my iPad, pause the lesson, print the charts, and start fresh the next day with all five charts in my hands.  Thank you Jessica!


2 comments:

  1. You are most welcome :) I know I still owe you the updated geometry album... so I am glad I got something helpful for you right now! ;) hehe

    Legoboy and I found with the sand and water, we needed depth to get it accurate - spreading it out too thing compared to its height aids a material in losing its heat quickly, so your theory was probably right about 10 minutes being too long for your particular set-up. We did a LOT of experiments with this to figure out what the variables were. Hmm... he has a notebook around here somewhere about it... ;)

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  2. I was about to agree that depth helped a lot. And I think we made sure that we used the thermometer like a meat thermometer and didn't touch the sides of the pan, (or any bones.) I think we put ours in the fridge because it was warm outside already here?

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