Orange Orchards

Remember than when water freezes, it expands. When this happens in a human cell, the cell membrane breaks, killing the cell and producing frost-bite. When a plant cell freezes, the cell wall is broken. This also kills the cell and the plant loses its firmness. This is why frozen celery has no crunch.

When oranges freeze, their insides become mush. If the oranges are fully ripe, they can be immediately squeezed for their juice, but if they are not ripe, they are lost. Thus, when a frost (a large mass of cold air that can freeze plants) comes to an orange grove, it can mean the loss of an entire crop. Fortunately, oranges are grown in warm climates so frosts are rare, however they must be dealt with when they come.

When a frost comes to an orange grove, the cold air takes heat from the land, the trees and the fruit. As they lose heat, their temperature goes down. If enough heat is removed, the temperature will drop to the freezing point of the fruit, killing the crop.

When a frost is predicted, one of the ways that farmers deal with this is to spray water all over the orchard. Then, when the cold air moves in it takes heat away from land, the trees and the fruit but it also takes heat from the additional water. Since such a large amount of water has a very large heat capacity, the cold can take a great deal of heat from the water without getting much colder. As a result, the cold air will not be able to bring the temperature down low enough to freeze the fruit.