Why Don't Lakes Just Evaporate or Seep Into the Ground?

Surprisingly, despite the sun's heat, lakes don't visibly evaporate like a glass of water. There are two main reasons for this: first, the amount of water present in lakes and large water bodies is huge (at least compared to what you might have in a beaker/tub). Therefore, the process of evaporation is quite slow, which is why you don’t notice the difference in their water levels. Having said that, in theory, lakes and ponds should (and do) dry up after a certain period, ranging from a couple of weeks to a few months, depending on how large the water body is. Fortunately, that doesn’t happen too often, thanks to the water cycle, which makes up for the water loss due to evaporation.