The blistering East Coast and Pacific Northwest heat waves are doubtless sending throngs to the beach and pool to cool off. That’s trading a case of heat prostration for a chance at sunburn. Luckily a number of iPhone apps aim to keep you from frying with advice and reminders. Here is a look at four apps. The easiest of the four to use, Sun Alert Lite has three dials with icons on them, one dial for skin type, one for the S.P.F. of your sunscreen, and one for weather conditions. The skin type dial provides adequate explanation of pigmentation, such as “Light brown skin, no freckles, good tanning ability,” to accurately pick your type. S.P.F. is self-explanatory, but the environment dial may require some thought. For instance, at my downtown pool, where the chairs are on a grass lawn, do I choose “sunny urban” or “park open field?” When the dials Read More