"When you use sprinklers to prevent freezing injury, you are using the energy that water releases when it freezes, and changes from a liquid to a solid, to keep the temperature in the ice right at the freezing point – 32 degrees F. As long as you keep the ice wet, the ice temperature will stay at 32 degrees F. If the ice dries out and water starts to evaporate from the ice, the ice will get colder than the air temperature as it evaporates."
https://www.canr.msu.edu/news/using_sprinklers_to_protect_plants_from_spring_freezes
