Albedo reflectance and bi-hemispherical reflectance (e.g.,). These calculations are based on the bidirectional reflectance distribution function (BRDF), which describes how the reflectance of a given surface depends on the view angle of the observer and the solar angle. BDRF can facilitate translations of observations of reflectance into albedo. Earth's average surface temperature due to its albedo and the greenhouse effect is currently about 15 °C. If Earth were frozen entirely (and hence be more reflective), the average temperature of the planet would drop below −40 °C. If only the continental land masses became covered by glaciers, the mean temperature of the
Albedo 0.39 light it receives that is reflected back into space. The album title refers to the average albedo value of the planet Earth as it was in 1976. From the explanation on the back of the LP cover : ""The reflecting power of a planet or other non-luminous body. A perfect reflector would have an Albedo of 100%. The Earth's Albedo is 39%, or 0.39"". As with "Heaven and Hell", it was performed at the Royal Albert Hall in 1977. The album reached #18 on the UK Album Charts. In 2011 the album was included along with "Heaven and Hell" and