Atmospheric duct by the ionosphere. The reduced refractive index due to lower densities at the higher altitudes in the Earth's atmosphere bends the signals back toward the Earth. Signals in a higher refractive index layer, "i.e.," duct, tend to remain in that layer because of the reflection and refraction encountered at the boundary with a lower refractive index material. In some weather conditions, such as inversion layers, density changes so rapidly that waves are guided around the curvature of the earth at constant altitude. Phenomena of atmospheric optics related to atmospheric ducting include the green flash, Fata Morgana, superior mirage, mock mirage
Night Waves Night Waves Night Waves was a radio programme broadcast on BBC Radio 3. The BBC described it as "Radio 3's flagship arts and ideas programme". "The Guardian" said in May 2010 "...the king of radio arts programmes is undoubtedly "Night Waves", a programme so clever that it regularly makes me stand still and listen, usually halfway to the dishwasher with a plate in my hand...It's the desire to untangle arguments, to lift up their corners and see what lurks there. There's a gleeful range of references too...and a relish for intelligent debate." It was broadcast every Monday to Thursday evening,