Recent studies of ice ageschoose one: a. suggest that the entire earth was covered by glacial ice in the late paleozoic, called "snowball earth."b. have dated events by analyzing wood trapped in glacial deposits, the oxygen-isotope ratio in marine sediments, and tillite deposits. c. have indicated the formation of paleosols during glacial periods, suggesting that glaciers formed under temperate conditions in some regions. d. reveal fewer large ice ages, fewer subdivisions, and less complexity than was originally thought.

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.

Just do the math, then think

This type of energy is called radiant energy.

This question has already been answered by someone else.here is a link.  hope that it .