<P> Hailstorms are precipitation in the form of ice, with the ice not melting before it hits the ground . Hailstones usually measure between 0.2 inch (5 millimetres) and 6 inches (15 centimetres) in diameter . A particularly damaging hailstorm hit Munich, Germany, on July 12, 1984, causing about $2 billion in insurance claims . </P> <P> An ice storm is a type of winter storm characterized by freezing rain . The U.S. National Weather Service defines an ice storm as a storm which results in the accumulation of at least 0.25 inch (6.4 mm) of ice on exposed surfaces . </P> <P> A cold wave (known in some regions as a cold snap or cold spell) is a weather phenomenon that is distinguished by a cooling of the air . Specifically, as used by the U.S. National Weather Service, a cold wave is a rapid fall in temperature within a 24 - hour period requiring substantially increased protection to agriculture, industry, commerce, and social activities . The precise criterion for a cold wave is determined by the rate at which the temperature falls, and the minimum to which it falls . This minimum temperature is dependent on the geographical region and time of year . </P> <P> A heat wave is a period of unusually and excessively hot weather . The worst heat wave in recent history was the European Heat Wave of 2003 . A summer heat wave in Victoria, Australia, created conditions which fuelled the massive bushfires in 2009 . Melbourne experienced three days in a row of temperatures exceeding 40 ° C (104 ° F) with some regional areas sweltering through much higher temperatures . The bushfires, collectively known as "Black Saturday", were partly the act of arsonists . The 2010 Northern Hemisphere summer resulted in severe heat waves, which killed over 2,000 people . It resulted in hundreds of wildfires which caused widespread air pollution, and burned thousands of square miles of forest . </P>

Which of the following types of natural disaster has no definite beginning and end