On the force of vertical winds in the upper atmosphere.

For many decades vertical winds have been observed at high altitudes of the Earth's atmosphere, in the mesosphere and thermosphere layers. These observations have been used with a simple one dimensional model to make estimates of possible altitude climbs by biologically sized particles deeper into the thermosphere. A particle transport mechanism is suggested from the literature on auroral arcs, indicating that an altitude of 120 km could be reached by a nanometer sized particle which is higher than the measured 77 km limit on the biosphere. Vertical wind observations in the upper mesophere and lower thermosphere are challenging and so we suggest that particles could reach altitudes greater than 120 km, depending on the magnitude of the vertical wind. Applications of the larger vertical winds in the upper atmosphere to astrobiology and climate science are explored.