ATOC 181 Lecture Notes - Lecture 4: Microsoft Powerpoint, Time Bomb, Photon
7 Jun 2018
School
Department
Course
Professor
LESSON 4
The Earth and Its Atmosphere Part 3
***WATCH VIDEO ON MyCourses: talk about 4 layers, ions***
Vertical Structure of the Atmosphere (Temperature)
- 4 layers
- near 20 degree Celcius near the surface in average?
- Temperature of air above the surface is warmer around Equator and decreases with
altitude, as goes towards the pole
- Globally averaged temp is 15deg near the surface
Variability of Temperature Distribution (Climate scale)
• Ouagadougou in Burkina Faso, Africa: 12oN
o Temperature decreases up to tropopause and increases in stratosphere
o Not much variation in temperature between summer and winter
o Near the equator
o Not much temperature variation during year
o There is variation in daily basis, but in general not much variation in average
temperature
o 16km to tropopause during the year. Thus, the height of the tropopause does not
change during the summer and the winter; it stays the same.
• Edmonton (530N)
o Data taken in January and July
o Large difference in the troposphere
o Much colder near surface
o Temperature increases in 1st km: called temperature inversion where temperature
increases with height
o Whenever have inversion, very stable atmosphere
o Tropopause in Jan is lower than in July: there is a variation in the height of the
tropopause
o Even tropopause height will increase
• Davis (Antarctica)
o Pretty much same temperature in summer and winter
o 22 degree Celcius warmer in troposphere than on surface in winter
o Temperature in stratosphere same in winter as on surface
• Ca’t use sae odel in different locations
o take data for years, update regularly and determine standard temp profiles
Graph For Temperature Variability (Temperature vs Altitude): Standard Temperature Profiles
• For Tropics, only one curve, as not need to be different, for the temperature variation of
the vertical atmosphere is the same during summer and winter
find more resources at oneclass.com
find more resources at oneclass.com
• For Arctic, 2 curves for variation in temperature during summer and winter
• Same for mid-latitude like here: 2 curves
• Used by scientist to test hypothesis, ideas and assess level of knowledge.
o Representative of climate values used by scientists in atmospheric models
• In the tropics (low latitudes), the vertical temperature profiles distribution and
tropopause height do not change much between summer and winter
• Vertical temperature difference between summer and Winter becomes larger as the
latitude increases where the height of the Tropopause increases in Summer.
• Height of Tropopause higher in summer than in winter
Ionosphere
• The Earth’s ioosphere is a part of the upper atmosphere, comprising portions of the
mesosphere, thermosphere and exosphere from about 85 to 600km
• Not part of the layer we talked about (previously described in lecture 3) in terms of
composition and temperature
• Is of interest to people working in telecommunications
o lots of electric particles present
o Presence of magnetic field
• Electrons removed from atoms by high energy solar x-rays (ionization) create currents
along the Earth magnetic field at various levels above the Earth
• Cirulate alog the Earth’s ageti field
Earth Magnetic Field
• Earth has magnetic field
o The geographic North pole corresponds to the south magnetic pole, while the
geographic South pole corresponds to the north magnetic pole
o Once in a while, they invert in scale in millions or more years
• Every time that have electron released in atmosphere, they may be subject to currents
due to magnetic field
• Several layers of ionosphere due to composition.
o nitrogen molecules destroyed by X rays
o some of the atoms bombarded by UV rays, escaped and enter magnetic field
• Depending on regions where have more molecules, can have more N2 than oxygen, which
will have different reactions.
• The composition of the layers of the Ionosphere changes much between day and night
o Day: sun will bombard atmosphere UV radiation
o At night, no such radiation
o Large difference between night and day.
o At night, high altitude atoms are excited by high energy cosmic rays only
o During day, there are 4 layers of ionosphere
▪ Each of them has one constituent that interacts with cosmic and solar rays
(see graph in power point on Mycourses)
o At night: 2 layers only
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
***watch video on mycourses: talk about 4 layers, ions*** Temperature of air above the surface is warmer around equator and decreases with altitude, as goes towards the pole. Globally averaged temp is 15deg near the surface. During daytime, due to the amount of electrons, this refraction might not occur, so disturbances and signals might disappear: radiowaves: not bounce towards earth surface, escape, rac: canadian association of radio amateurs. In the past, old radio can also receive am frequencies. Aurora borealis: outcome of ionization in atmosphere: atoms are excited, electrons will move to higher level of energy. In the north, there is a higher chance to see them time. **time bomb: putting hole in ice, light/provide fire over it and will explode due to presence of methane under the ice. Condense to become clouds or transported in air through winds. Showing where water vapour becomes liquid in picture.
