Atmosphere of Earth they penetrate more deeply. The various layers of Earth's ionosphere, important to HF radio propagation, begin below 100 km and extend beyond 500 km. By comparison, the International Space Station and Space Shuttle typically orbit at 350–400 km, within the F-layer of the ionosphere where they encounter enough atmospheric drag to require reboosts every few months. Depending on solar activity, satellites can experience noticeable atmospheric drag at altitudes as high as 700–800 km. The division of the atmosphere into layers mostly by reference to temperature is discussed above. Temperature decreases with altitude starting at sea level, but variations in this
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,