Think of the word convert as meaning change, whether it is a person who adopts a new belief, or a changing action, such as when you convert dollars into euros. Many times we can catch a word's meaning by looking at its origins. In this case, the Latin con means around, while vertere means turn..
Maple sap runs best when it freezes at night (e.g. in the high 20-degrees Farenheit range) and then warms up above freezing the next day (in the range of 40-degrees Farenheit and hotter). If it stays warm at night and warm during the day or if it freezes at night but barely goes above freezing the next day, sap does not flow as well or hardly at all.
Michigan State University Extension provides the following information about maple syrup production in Michigan and how it is a good example of a natural resource enterprise. maple syrup season lasts only four to six weeks in the early spring when maple trees are dormant (i.e. before leaf buds swell and break open). When daily temperatures start to consistently rise above freezing maple sap begins to push up from the roots into the upper portions of the tree.