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.
Alert, vigilant, watchful imply a wide-awake attitude, as of someone keenly aware of his or her surroundings. Alert describes a ready and prompt attentiveness together with a quick intelligence: The tourist was alert and eager to see the sights. Vigilant suggests some immediate necessity for keen, active observation, and for continuing alertness: Knowing the danger, the scout was unceasingly vigilant.