British Antarctic Survey has conducted long-term studies into the ionosphere to gain a better understanding of its basic physics. These have implications for studying space weather events including sun storms that have an impact on global telecommunications, navigation and power systems. The ionosphere is the region of the Earth's atmosphere extending above 70 km altitude. The ultra-violet component of sunlight ionises a significant fraction of the atoms and molecules present. The region was first discovered when scientists found that ionisation causes the reflection of radio waves.
Carbon dioxide is a strong radiator of infra-red.
At ground level this helps to give it its 'greenhouse' properties, but in the upper atmosphere the radiation is lost to space and so the air cools.