Lake turnover occurs when the layers of water with noted temperature differences begin to mix together and the water and debris that has been sitting at the bottom of the lake begins to mix with the layers of water above it.
Definition of cautious. : careful about avoiding danger or risk cautious investors cautious optimism.
A feeling of general confidence regarding a situation and/or its outcome coupled with a readiness for possible difficulties or failure. I've prepared for this exam for weeks, so I have a cautious optimism that it will turn out well. It's best to exercise cautious optimism when starting any new business.