These collect rainwater. But the device is designed to collect water even when there is no rain.

VOA: special.2010.07.13

Now this is a rain gauge, and it's sitting on a roof of a building, and when the water falls into this gauge, it sends a signal to the logic unit of the computer, which immediately notifies the memory bank of the computer to seek out its instructions for a rainy day.

这是一个雨量测量器，安装在一个楼房的,屋顶上，当水流入到这个测量器，它就给计算机的逻辑部件发送一个信号，计算机立即通知内存条,为下雨天找出相应的指令。

哈佛公开课 - 计算机科学课程节选

About fifteen centimeters of wet snow has as much water as two and one-half centimeters of rain.

VOA: special.2010.01.05

About seventy-six centimeters of dry snow equals the water in two and one-half centimeters of rain.

VOA: special.2011.01.11

Snow contains much less water than rain.

VOA: special.2010.01.05