Abstract
The daily and anual changes of the radar detection range were observed for more than a year from 1967 to 1968 In spring and summer, for several hours past noon of fine days, the detection range usually increases and super-refraction or duct condition is considered to occur, while, at midnight or in the early morning it decreases. In autumn and winter, few daily changes are found and standard condition or slight sub-refraction is observed for all day long.
