Monthly Archives: November 2013

Weather Sticks-Mother Nature’s Psychrometer

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I first saw a weather stick years ago and was intrigued by how reactive a tree branch might have to humidity. I’ve been wanting to write this blog entry for years, since before I knew about blogging actually, if that’s possible. Basically, the more humid it is, the more your weather stick (tree branch) will react.

This could be a fun way for you and your kids to make connections between weather and how it affects living things (and dead things)! Collecting weather sticks is a great excuse to go on a hike and explore the woods together.

How to

1. Go enjoy a day outdoors together and begin your hunt for your weather stick.

2. I have only tested branches from conifers so far: a Balsam Fir and a Cedar tree. It could be fun to grab a few different kinds to see how different species react.

3. Try to collect from those trees that have already died and/or fallen to the ground that way you don’t have to kill a tree. It is not necessary to kill a tree to find a good weather stick.

4.Once you locate your desired tree, you can cut the trunk above and below the branch you wish to have as your weather stick. I used a set of pruning shears for this. If using a saw or knife, please be careful and children should be supervised while doing so.

5. Once you have your stick chosen, cut away all excess branches and twigs extending from the weather stick.

6. Shave off the bark if there is any left on the branch. This can be a delicate process since weather sticks are typically thin. Be careful not to snap your branch.

7. Once the bark is removed, your stick is ready to be mounted.

8. Mount stick as you wish, see what works and what doesn’t; just make sure that nothing will inhibit the movement of of the branch as the humidity fluctuates. I once set one up along a windowsill, so that while indoors, I could write details about the weather on the window to track the stick’s changes. Whenever the stick moved up or down, I would make a mark on the window and write the temperature and whether or not it rained or snowed that day.

Now watch for changes in your stick(s)!

Photos

Notice the Changes

In the first photo you will see two thumbtacks in the wall where the tip of the weather stick used to be. The thumbtacks represent a day where humidity was recorded to be %100, on an overcast day. The thumbtacks are at the base of each drawn arrow. The branches in this photo are where they normally go during dry, sunny weather.

*you will notice that the cedar branch (top weather stick) went down in high humidity (typically “poor’ weather) while the Balsam Fir (bottom branch) went up. There is a scientific theory based on wood-cell physics that will explain why some branches go up and others go down in identical weather conditions, if you follow this link.

http://www.new-potato.com/wstick/Science/science.html

sticks-move

* Arrows indicate movement from overcast, high humidity to dry, warm conditions.

In the next photo, I have overlaid two snapshots of the sticks during different weather conditions, taken 2 days apart, so that you can see how much movement you might notice from day to day.

sticks-overlay

* Black dots beside thumb tacks indicate high humidity conditions.

If you do end up using a Balsam Fir (as I have a few times) and you want the stick to perform by rising in “good” weather (dry) and falling in “poor” weather (high humidity), simply install it upside down 🙂 How we feel about the changes in humidity is relative though: A farmer might see high humidity as an indication of rain to come (good for crops) whereas too many dry days means drought and potentially a crop burned by the sun. Install your stick so it performs the way you wish.

Happy weather monitoring!