Atoms Under the Floorboards by Chris Woodford

Author:Chris Woodford
Language: eng
Format: epub
Publisher: Bloomsbury Publishing

The other reason why radio waves travel so far is even more clever. As most people are well aware, if you use an AM (medium wave) radio, you can hear all kinds of crackling, buzzing foreign radio stations at night that you can’t detect during the day. That’s all down to a part of Earth’s atmosphere called the ionosphere, roughly 60–500 km (40–300 miles) above your head (at least six times higher than jet planes fly). It has that name because it contains ions (atoms split apart into positively charged bits by losing some of their negatively charged electrons), which means that it conducts electricity. The ionosphere is dramatically affected by radiation from the Sun, so the way it behaves changes radically between daytime and night. During the daytime the lowest layer of the ionosphere soaks up radio waves and prevents them from travelling very far. At night that effect diminishes, enabling higher layers of the ionosphere to reflect radio waves like a mirror, intercepting signals that would normally shoot out into space and shining them back down to the planet’s surface. Some radio waves repeatedly bounce between the ground and the ionosphere, effectively carrying them from one side of the planet to the other.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.