Monday, November 3, 2014

Teach hiking kids to predict weather using plants

Open slower petals on some plants means no rain.
Photo courtesy of raelb / Photoree.
Here’s a neat trick to teach kids on a hike: Predicting weather with plants.

Though often dismissed as an old wives’ tale, outdoorsmen long have used the change in some plants’ appearances to make a good guestimate of what the weather holds. That’s because changes in atmospheric pressure signal to some plant to “prepare” for coming rain. This is an evolutionary function of such plants, which have a greater chance of surviving if rain doesn’t wash away their pollen.

For example, on a dry day the leaves of a shamrock will remain fully exposed to the sun, like an open palm. As the likelihood of rain increases, the leaves fold in, like a hand making a fit. The same occurs with the petals of bindweed, chickweed, chicory, clover, dandelions, morning glory, tulips and wild indigo.

The scales of some pine cones also will open during dry weather as they stiffen and shrivel. As humidity rises, however, the scales regain their moisture and flexibility, and so they close up.

If hiking near wetlands, sniff the air to determine the weather. If the air is smelly, expect rain. That’s because the lower pressure that precedes a storm allows more methane to be released from the soggy ground.

Learn about trail guidebooks available in the Hittin’ the Trail series.