Former Phillies manager Charlie Manuel, considered a master in the art of hitting, stated that once the weather turns hot, the bats heat up, and home plate becomes a launching pad.

He had science and intuition on his side. But what could explain what happened at Citizens Bank Park on a damp Monday night, when the Phillies and Arizona Diamondbacks combined for a home-run record that couldn’t be attributed to heat?

Temperatures were in the mid-70s, hardly meltdown level. Then, we have to consider the little matter of pitching, and one wonders whether the balls are getting a jolt of juice these days.

But the hitters might well have had an invisible force going for them: After the rains backed off, the atmosphere remained thick with water vapor.

The dewpoints — true measures of atmospheric moisture, as opposed to “relative” humidity — were in the low 70s, about where they are during heat waves.

As counterintuitive as it might seem, moist air even at moderate temperatures is more buoyant and lighter than hot, dry air, when dewpoints might be in the 50s or 60s, notes Jim Eberwine, meteorologist and longtime baseball fan.

“The molecules in water vapor are fewer and lighter than dry air,” said Eberwine, whose career at local National Weather Service offices spanned 13 managers -- coincidentally, that matched the number of homers hit by both teams Monday night at the Bank.

“The winds weren’t that much of a factor,” he added.

That said, Eberwine believes that the leadoff homer by Jarrod Dyson needed no molecular assistance. “I think that first-pitch home run was going out no matter dry or humid,” he said.

That was the first of the 13 homers, a single-game major-league record.

Jake Arrieta, who has given up a few bombs this season, should at least have the atmosphere on his side Tuesday night. Dewpoints are due to fall into the 40s.