Sea level the warmer water expands. For at least the last 100 years, sea level has been rising at an average rate of about per year. Most of this rise can be attributed to the increase in temperature of the sea and the resulting slight thermal expansion of the upper of sea water. Additional contributions, as much as one-quarter of the total, come from water sources on land, such as melting snow and glaciers and extraction of groundwater for irrigation and other agricultural and human uses. Pilots can estimate height above sea level with an altimeter set to a defined barometric pressure.
Centigrade 232 another Centigrade 232 poem ("Ode To A Crystal Set") appear on the CD's opening track "Second Degree Soul Sparks". In October 2007, Voiceprint Records re-issued "Centigrade 232" in a package containing both a reprint of the 1977 book and a CD of the 1986 recitations. Voiceprint Records label head Rob Ayling passed a copy of the cassette tape of Calvert's recitations to Dave Brock and asked him to set some of the titles to music. The music was played by the then current line-up of Hawkwind, but some titles were lost at the mixing stage delaying the release until August