Book 30, Question 42
Why are there vineyards and orchards near the Great Lakes?
The big lakes warm slowly and cool slowly, so they act like giant temperature moderators.
In spring, cool lake air delays blossoms until after danger of frost has passed. In fall, warm water keeps frost away longer. The Niagara region of Ontario uses this effect to grow peaches, cherries, and grapes. Without the lakes, winters in these places would be harsher.