Etta Nirk, age 11, of Lethbridge, Alberta, Canada, for her question:

What exactly is the wind?

The wind itself is invisible, which makes any explanation of it hard to believe. We can say that it is nothing more than moving: air, though when you think of the devastating destruction done by hurricane winds, this theory seems rather ridiculous. However, let's test the idea on a small scale. Hold up a strip of paper and puff with all your lung power. You create a gust of moving air that makes the paper bend. The harder you blow, the more strength your small breeze has to push the paler. The best breeze you can blow is pitifully small, when compared with the oceans of air outdoors. Windy streams of moving air can blow clear across the continent. And the faster they blow the stronger they axe. A breeze moving at five miles per hour can ruffle the leaves. At ten miles per hour it can spread out a drooping flag. A strong gale of 50 miles per hour can whisk shingles off the roof and a 100 mile per hour hurricane wind can uproot trees. And all this invisible strength is nothing more than currents of air, moving from place to place.