Question: I live in Michigan, not far from the east shore of Lake Michigan. We’ve been having a lot of what the weatherman calls “lake effect snow” and I think I understand what causes it. What I’m curious about though, is if the size of the lake matters? Does this only happen for a “Great” lake, or can it happen with smaller lakes also? — MD, Holland, MI
Answer: For those not familiar with the term, let me first explain what qualifies as “lake effect snow” (LES). This type of snow often occurs when cold air blows over warm water. Click on the thumbnail below to see NOAA’s LES graphic.
The cause of LES is explained by thermodynamics. Water holds its heat much better than air: The specific heat of water is 4.184 J/g°C (joules per gram-degree Celsius). What that means is: You need 4.184 J of energy to change the temperature of 1 g of water by 1 °C. By comparison, the specific heat of air is only 1.020 J/g°C (depending on its temperature, pressure, and humidity).
So in compliance with the laws of thermodynamics, when cold air comes in contact with warm water, the air will absorb heat ...