By Tess DeMeyer When athletes slide down the slopes or drop in on the halfpipe in Beijing at the 2022 Winter Olympics, there won’t be fluffy, nature-made powder underfoot. But how much of an impact will artificial snow actually have on the competition? Maddie Mastro knows her snow. The 21-year-old snowboarder from Wrightwood, Calif., can expound on the differences between the flakes upstate at Mammoth Mountain (“it’s really heavy and wet”) and the powder in Colorado (“it’s typically dry and fluffy”), so she can tell instantly when the snow in a halfpipe is fake. Mastro says artificial snow—lik…