11. Vertical Temperatures and Zones
•Troposphere
– Lowest layer of atmosphere
– Temperature decreases with
height on average – 6.5 oC/km
– Depth varies from 8-18 km
– Characterized by vertical and
horizontal air motion; Location of
all "weather" phenomena
– Characterized by 2 regions
•Planetary boundary layer(~ 1 km
depth)
•Free troposphere
12. Vertical Temperatures and Zones
•Tropopause
– Layer of air immediately
above troposphere
– Temperature is isothermal
– Varies in depth
•Stratopause
– Isothermal conditions
– Forms boundary between
stratosphere & mesosphere
13. Vertical Temperatures and Zones
•Stratosphere
– Temperature increases with height to
altitude of 45-55 km
– Very stable region with little vertical
mixing of air
– Few clouds/no weather
– Warmer temperatures due to
absorption of UV radiation
– Complex chemistry involving NO, OH.,
NH3, O, O2, O3, Cl + other species.
– Chapman Reactions:
O+ O2 + M O3 + M
O + O+ M O2 + M
O3 + h O2 + O + Heat
for h corresponding to 0.24
0.30 m
14. Vertical Temperatures and Zones
•Mesosphere
– Temperature decreases with height up
to an altitude of 85 km
– Coldest region of atmosphere
– Rapid vertical mixing
– Photo dissociation of oxygen:
• O2 + h 2O + Heat
for h corresponding to 0.18 0.24
m
• Chapman Reactions:
O+ O2 + M O3 + M
O + O+ M O2 + M
O3 + h O2 + O + Heat
for h corresponding to 0.24 0.30
~m
15. Vertical Temperatures and Zones
•Thermosphere
– Extends from 90-95 km to ~ 1000 km
– High thermodynamic temperatures
(~1200 oC)
– Solar energy absorbed by N2 & O2
•Results in photo-ionization
•Ionized layer called the ionosphere
–Reflects radio signals