Inversion

Many of Utah’s valleys experience “inversions” in the winter and spring.  Under calm conditions and clear skies, a temperature inversion forms when the cold air settles to the lowest spots, displacing warmer air.  Historically, the most successful sites for growing fruit along the Wasatch Front were on the east bench.  This elevation escaped the coldest midwinter temperatures, and was less prone to spring frosts during bloom.  However, this elevation advantage can be lost when cold air cannot “drain” and pools up behind hedges or other obstructions (see figure). 

 

 

When strong temperature inversions form during critical stages of flower bud development, some commercial orchards run large fans that mix the air, displacing cold air near the ground and bringing warm air back down into the orchard.  Home gardeners in low-lying areas are going to have more risk of spring frost, and should select late-flowering species or may need to forego planting fruit trees.