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.
self-important (Adjective). Having, or behaving as if having, too high an opinion of one's own importance. The assistant manager was a self-important fellow who strutted about the office barking instructions.