The Winter edition of the QRP Amateur Radio Club International journal, QRP Quarterly, has an article proposing that the author's minimalist DX contacts on 160M were via sporadic E. He states that Kenneth Davies' latest book, Ionospheric Radio Waves, cites substantial evidence that "ever present" sporadic E exists on MF due to meteor scatter. Meteor scatter lasts 600 times longer at MF than at VHF. There is quite a good development of the idea, with evidence, in the magazine article. The article is not available online, as far as I know.
I thought I would mention the book in case anyone is interested in digging into this area for MW listening.
Garry
I fixed a mis-statement, above. Should be 600 times longer at MF than at VHF (not HF).
Edited by - Garry Nichols on 3/17/2013 7:12:14 AM