Early investigations of the F2-layer critical frequency revealed that it does not behave at all in the manner of a simple Chapman layer but displays many outstanding abnormal phenomena which may involve some basic mechanisms.

• 电离层的静日变化并不是人们所熟知的Chapman层规则变化,而是呈现出非常多的异常现象,这些异常现象涉及到控制电离层的各种因素。