中文摘要：

雨水具有一定的放射性．对雨滴下落过程进行了模拟，采用一般的放射性仪器，通过对水滴的放射性γ射线的测定表明：雨水对空气的冲刷可以有效收集空气中的放射性物质，是雨水天然放射性的来源之一。并且通过对于雨水中γ射线的数值分析表明：水汽的凝结也是雨水具有放射性的原因之一。

英文摘要：

The rainwater radioactivity has been observed. We simulated the course of the rainwater dropping down, and the gamma ray in rainwater radioactivity had been measured using general radioactive measurement instrument. The results showed that rainwater scouring air is an effective way to collect the radioactive nuclides, and it is one of the reasons why rainwater has natural radioactivity. The results of gamma ray numerical analysis showed that the course of vapor condensation is also one of the reasons why rainwater has natural radioactivity.