Saturday, March 5, 2011

Mesosphere facts

Here ar some interesting facts about mesosphere.The mesosphere cools with increasing height until it reaches the mesopause or minima with summer temperature at about −130 °C or lower, then it starts to warm again with height in the lower thermosphere. The mesosphere extends from between 31 and 50 miles (50 to 80 kilometers) above the earth's surface. The mesosphere is characterized by temperatures that quickly decrease as height increases with temperatures as low as -93°C at the top of the layer. Only rockets and meteors travel through this layer.And this is where meteors usually burn up when they enter Earth’s atmosphere.The mesosphere is the coldest layer of the atmosphere, where the thin air is often turbulent and strong gusty winds blow—it even contains ice aerosol clouds in summer.The boundary between the stratosphere and the mesosphere is known as the stratopause.The percentage of Nitrogen and Oxygen is about the same in the mesosphere as it is at sea level but the atmospheric pressure is much lower. The lapse rate in the mesosphere is approximately 2°C/1000 m.The mesopause marks the boundary between the mesosphere and the thermosphere.Due to reactions taking place in the thermosphere and upper mesosphere, mesospheric air is enhanced in reactive nitrogen compounds, which can effect ozone. Furthermore, mesospheric
air is enhanced in CO  and is expected to show enhanced levels of molecular hydrogen and depleted values of water vapour, which may influence the chemistry of OH radicals.Long-period oscillations in the period range between 2-30 days, interpreted as planetary wave (PW) signatures, have been analysed using daily upper mesosphere/lower thermosphere wind measurements near 90 km over Collm (52°N, 15°E) in the time interval 1980-2005. Strong interannual and interdecadal variability of PW are found.