KnowitAll Project- Wallace and Hobbs #3 – Atmospheric Constituents and Vertical Profile

by Joe Archive on January 23, 2008

a href=”http://blog.joeandersen.com/2008/01/knowitall-project-wallace-and-hobbs-2.html”Prev/abr /br /1.2.4 – Some other atmospheric constituentsbr /br /Nitrogen – low chemical inertness and solubility, without being too massive. Most of the nitrogen released by vulcanism since the formation of the planet has remained in the atmosphere. Chemical processes have removed most of the other species, so nitrogen has come to dominate the atmosphere.br /br /Sulphur is quickly oxidized and dissolves in cloud water and forms sulphuric acid – Acid rain.br /br /Argon is very abundant for a noble gas, dominated by ^{40}Ar, a byproduct of the radioactive decay of potassium. Radioactive decay is the source of most of the helium in our atmosphere also.br /br /1.3 The Distribution of Atmospheric Mass and Gaseous Constituents.br /br /The atmosphere exerts a downwards force on the Earth’s surface. Mean atmospheric pressure at the surface is approximately M_a g_0 /(4piR_E^2), roughly 10^5 Pa.br /br /1.3.1 – Vertical profiles of pressure and densitybr /br /Vertical variability of pressure and density is much larger than horizontal and temporal variability. Within the lowest 100km, the density remains roughly constant, meaning that the logarithm of pressure approximately decreases with altitude.br /br /log[p(z)] ~ log[p(0)] – Bzbr /br /ln[p(z)/p(0)] ~ -z/Hbr /br /H is called the scale height of the atmosphere: p(z) ~ p(0)exp(-z/H)br /br /For the standard atmospheric values, the scale height of the atmosphere is ~7km. The atmosphere is remarkably thin compared to the earth. Half its mass lies below the 500mb (~5.5km). 99% of the atmosphere lies within 30km of the surface.

Previous post:

Next post: