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On a still day, clouds move slowly across the sky. How much of this is due to Earth’s rotation? Do clouds seem to move faster at the equator?

Philip Welsby, Edinburgh, UK

I straighten my hair and my friend curls hers with a heated hair wand. Humidity, sweat or washing instantly reverses the process. My wavy hair goes frizzy in humidity, but her straight hair doesn’t. What is happening?

Nina Dougall, Malmsbury, Victoria, Australia

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