|NASA satellite photo image of a full blown lake effect event over Michigan (and Ontario)|
It's interesting to note in the picture above that bands of snow are generating from Lake Michigan, Lake Superior and even the little lake north of Superior, Lake Nipigon.
Anyway what were we talking about?
"Affect" is an action word that exerts influence on a something or someone. "Effect" is almost always a noun and describes the result or outcome of something exerting influence.
Cold air over unfrozen water, and steady wind are two of the things that affects weather in the Great Lakes region causing what has come to be known as lake effect weather.
Rarely the action word "affect" is used as a noun in this sense: His lack of affect made him seem like a boring person. In this case "affect" is referring to the ability to influence.
Affect - action
Effect - result