It is amazing to watch the natural miracle of plant life on earth moving from dormancy to emergence to maturity. Much of life is about momentum. Accumulation of growing degree days is about momentum. Accumulating warmth and energy available for plant growth. GDD, or growing degree days, is a weather-based indicator for assessing crop development and pest development rates. In physics I vaguely remember that momentum is multiplied by velocity and usually ends in collisions. With plant life momentum usually ends in revisions. Accumulations of warmer ambient temperatures builds the momentum giving the season the perfect name… Spring.