又到冬天了，紛飛的白雪給大地披上銀裝。人們賞雪、玩雪不亦樂(lè)乎。但你沒(méi)有注意過(guò)下雪的天氣其實(shí)都不是太冷呢？下面就來(lái)為您解答這個(gè)疑惑。

    Snowing does not cause the warmth, the relative warmth causes the snow.

    During very cold weather the capacity of the air to contain moisture is greatly reduced. What water vapor remains is deposited as frost. At the same time, evaporation is reduced and therefore air humidity remains low. In these conditions snow cannot form.

    Warmer air can hold more moisture before the saturation point is reached and the water vapor begins to condense out. So when warmer air moves into cooler areas, not only do we feel the increase in temperature, but the excess vapor precipitates as snow.