Albedo (Latin albedo – a whiteness, from albus – white) – the photometric size which characterizes reflective ability of a surface. The albedo is expressed by the relation of density of the radiant flow reflected by a surface, to density of the flow falling on it (as a percentage or in unit shares).

Whether you know that:

Was considered earlier that yawning enriches an organism with oxygen. However this opinion was disproved. Scientists proved that yawning, the person cools a brain and improves its working capacity.