You assumed it was osmosis — water seeping into your skin, puffing and puckering the outer layers like a raisin. It's a reasonable explanation. It's also wrong. Your fingers don't wrinkle in water ...

There's a belief most of us carry around like a comfortable lie: if you can't see the sun, it can't hurt you. Overcast sky? Leave the sunscreen at home. Drizzly morning? Your hands are fine exposed...