Which frost protection method involves applying water to protect crops from frost?

• A. Heaters
• B. Turbines
• C. Sprinklers
• D. Cloud rockets

Answer: (C)

Sprinklers protect crops from frost by using the heat released when water freezes. When water is sprayed on the plant canopy during freezing conditions, it begins to freeze on contact. The phase change from liquid to solid releases latent heat, which keeps the surface temperature around 0°C and prevents tissue temperatures from dropping below freezing. This direct supply of heat is why sprinklers are effective: they maintain a protective thermal buffer as long as water keeps flowing and temperatures stay near or just below freezing.

In contrast, heaters warm the air around the plants, which can be energy-intensive and may create uneven warming. Wind machines or turbines mix the air to reduce frost risk but don’t add water. Cloud rockets or cloud-seeding approaches aim to alter radiative properties or create cloud cover, but they’re less reliable and not a standard frost-protection method for crops.