Curitiba (Southern Brazil) is the coldest of Brazil's state capitals; the greenhouse of the Botanical Garden of Curitiba protects sensitive plants.

Frost is ice that is formed when water vapor freezes onto a surface. It has a white, powdery appearance. It forms on cold surfaces when the temperature of the air is very low. It can destroy crops. This can cause mass hunger.

Many plants can be damaged or killed by freezing temperatures or frost. This varies with the type of plant and tissue exposed to low temperatures. Greenhouses help to protect crops from cold and frost damage.

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