雨的形成实验教材中的做法是:用酒精灯给烧瓶中的水加热使其变成水蒸汽,在瓶口上方附近用一表面皿挡住从烧瓶口冒出的水蒸汽,由于冷的表面皿和热的水蒸汽之间存在较大的温差,所以热的水蒸汽遇到冷的表面皿时,就在表面皿上凝结成小水珠,许多小水珠聚集在一起,就形成较大的水珠, The formation of rain experimental materials in the practice is: alcohol lamp to the flask heated water to steam, near the top of the bottle with a tableware to block the water vapor from the flask port, due to the cold surface dish And hot water vapor between the larger temperature difference, so hot water vapor encountered cold surface dish, on the surface to condense into small water droplets, many small droplets together to form a larger Drops,