Our Sun drives our Atmosphere
Interesting post at
Science Daily:
Boundary Between Earth's Upper Atmosphere And Space Has Moved To Extraordinarily Low Altitudes, NASA Instruments Document
Observations made by NASA instruments onboard an Air Force satellite have shown that the boundary between the Earth's upper atmosphere and space has moved to extraordinarily low altitudes. These observations were made by the Coupled Ion Neutral Dynamics Investigation (CINDI) instrument suite, which was launched aboard the U.S. Air Force's Communication/Navigation Outage Forecast System (C/NOFS) satellite on April 16, 2008.
A bit more:
CINDI's first discovery was, however, that the ionosphere was not where it had been expected to be. During the first months of CINDI operations the transition between the ionosphere and space was found to be at about 260 miles (420 km) altitude during the nighttime, barely rising above 500 miles (800 km) during the day. These altitudes were extraordinarily low compared with the more typical values of 400 miles (640 km) during the nighttime and 600 miles (960 km) during the day.
The height of the ionosphere/space transition is controlled in part by the amount of extreme ultraviolet energy emitted by the Sun and a somewhat contracted ionosphere could have been expected because C/NOFS was launched during a minimum in the 11-year cycle of solar activity. However, the size of the actual contraction caught investigators by surprise. In fact, when they looked back over records of solar activity, they found that C/NOFS had been launched during the quietest solar minimum since the space age began.
Emphasis mine and the Solar Minimum is staying minimum, there are no changes. We get the occasional Cycle 24 spot lasting for a few days but the Sun has been very quiet recently.
Posted by DaveH at December 16, 2008 5:22 PM