Read the course materials this week watch chapter 3 lecture in the link below http://forecast.uchicago.edu/lectures.html Look for an article related tot the materials in the uploaded file 500 words You are expected to submit a summary of a current cl

Geograph110_9_HeatEngine_AtmosphericCirculation3
 

Read the course materials this week

watch chapter 3 lecture in the link below

http://forecast.uchicago.edu/lectures.html

Look for an article related tot the materials in the uploaded file

500 words

1. You are expected to submit a summary of a current climate / environmental-related article from the mainstream press, along with your personal evaluation / reflection. Using a recent news article from a reliable source, please feel encouraged to explore topics that include extreme weather (e.g. winter storms, drought), climate change, energy (e.g. decreases in crude oil price, fracking, coal mining, nuclear power plants, alternative energy, etc), adaptation of animal behavior to recent climate change (including mammals, insects, fish, etc), policy related topics (international climate change conferences), and more. Due by February 25th.
   Guidelines of this assignment are:

   Article summary: Your own summary – do not copy from an original source (1 page).
   Reflection: Your own discussion about the topic(s) of the article. Please apply your knowledge from this course and incorporate it into your discussion (1 page)
   Maximum pages: 2
   Font type and size: Times New Roman/Times, 12-point size, double spaced
   Data: include source data 
   Figures and Tables (optional): include source data
   List of reference(s)

Earth’s radiation budget

We have learned about the greenhouse effect. Now, with the greenhouse
effect in mind, lets dive a little deeper and see what is happening in the
atmosphere.

The Structure of the Atmosphere

Temperature
varia3ons define the
atmosphere�s four
principal layers:
the troposphere,
stratosphere,
mesosphere, and
exosphere.
The ozone layer is
within the
stratosphere.

This picture represents the temperature profile of the atmosphere. As you will recall

from Week 2’s lecture, most gas molecules are within the lower atmosphere,

specifically, the troposphere. Within the troposphere, temperatures decrease with

increases in altitude. This is because incoming solar energy is absorbed by the Earth, a

blackbody, and back radiation from the Earth heats up the atmosphere (Gas molecules

in the atmosphere can be blackbodies, however, they are not as effective at absorbing

and maintaining heat as the solid Earth). Thus, temperature vertically decreases as

you move away from the heat source (the Earth).

Interestingly, there is an inversion within the stratosphere. Temperature increases

when you go higher in altitude. This makes stratosphere a very stable environment.

Warmer, therefore less dense, air sits on top of colder, therefore denser, air. With this,

the atmosphere in the stratosphere is very difficult to disturbed (thus stratified). This is

mainly because of the ozone layer, a layer that contains a relatively high concentration

of ozone, that exists within the stratosphere. As you learned in

�Geograph110_6_Greenhouse Effect III�, ozone in the stratosphere absorbs mainly
incoming shortwave energy. This is good for us because the ozone layer blocks ultra

violet light and other shortwave energy that are harmful to living organisms. This

absorbed incoming energy keeps the stratosphere warmer with increases in altitude.

The Atmosphere Screens Earth from Harmful

Solar Radiation

Shorter wavelength
gamma and X-ray

radiation and large
amounts of infrared

radiation are
completely absorbed
by the atmosphere.

The ozone layer
absorbs the most

harmful ultraviolet
wavelengths. Only
radio waves, visible

light, and some
ultraviolet radiation

reach Earth�s surface
relatively unimpeded.

Portion of the electromagnetic spectrum

A schematic image showing incoming and outgoing radiation and their interference
within the atmosphere. Purple bars represent incoming shortwave energy and red
bars are outgoing longwave energy. As you can see, the majority of shorter
wavelength energy is absorbed within the atmosphere and never reaches the
surface. Also, part of the outgoing back radiation is absorbed in the atmosphere
due to greenhouse gases.

Solar Radiation

Infrared radiation: Wavelengths longer than 780 nm.
Quickly absorbed and converted to heat in the upper few meters of a body of

water.

Ultraviolet radiation: (< 380 nm) Forms only a small fraction of total radiation.

Usually rapidly scattered and absorbed, except in the clearest body of water.

Visible spectrum :(400-700nm)
� Penetrates deeper into the sea.
ParJcularly important for

animals with vision.

� Approx. the same wavelength
as used by plants for

photosynthesis, so oLen called

photosyntheJcally acJve

radiaJon (PAR).

Absorption
Spectra of

Greenhouse Gases

The shapes of the
blackbody

spectra of Earth
and the sun

Percentage of
radiation

absorbed through
the atmosphere

Here is a re-cap of what we leaned:

• The radiation emitted by a blackbody has a characteristic wavelength
distribution that depends on the body’s absolute temperature (the Earth’s

blackbody radiation = infrared wavelength).

• “Percentage of radiation absorbed through the atmosphere”, absorption of
100 % means that no radiation penetrates the atmosphere. CO2, O3, N2O,

CH4, H2O are the media that absorb associated wavelength energy – and we

now know that these media are called greenhouse gases!

Outgoing spectrum of the Earth
with an atmosphere

This figure shows the Blackbody spectrum for objects with temperatures
ranging from 300 K (surface temperature) on a hot summer day, down to 220
K, about the coldest it gets in the atmosphere, up near the troposphere at
about 10-km altitude. The jagged-looking curve (denoted as “Atmosphere”) is
a model-generated spectrum of infrared light escaping to space from the top
of the atmosphere. This is jagged-looking, because CO2, water vapor, ozone,
and methane absorb specific wavelengths of outgoing energy emitted from
the ground.

MODTRAN MODEL
Please visit the following interactive Modtran Model site, developed by David Archer

of Chicago University to explore the Earth’s outgoing spectrum.

hGp://climatemodels.uchicago.edu/modtran/

http://climatemodels.uchicago.edu/modtran/

So what would the Earth’s surface
temperature look like from space if

the Earth had no atmosphere?

Outgoing spectrum of the Earth
With an atmosphere

270 K

Without an atmosphere, more energy will be radiated due to an absence of
the greenhouse effect. In fact, the outgoing spectrum will look like a
blackbody spectrum at 270 K (= -3 C�, 26.6 F), between the 260 K and 280 K
spectra shown in this figure.

Greenhouse Effect
What is the hottest planet in the solar system?

H2, He, O2

CO2, N2, H2O, SO2

The ho&est planet in the solar system?

Mercury – closest to the Sun – is not the ho&est. Very thin atmosphere composed of
H2, He, O2 – no greenhouse gases. The temperature is 426C during the day, -173C in
the shadow.

The atmosphere of Venus is very thick. It is composed of CO2 gas (96%), with some
nitrogen (3%) and a very small amount of water vapor (0.003%). Venus also has a
thick layer of sulfuric acid clouds. Although Venus is much further away from the
Sun, due its thick atmosphere made up of greenhouse gases, Venus remains the
same temperature no ma&er where you go on the plant; at the North Pole, day or
night: 461C

Mercury is hot, but Venus is ho&er (greenhouse effect)!

A greenhouse gas is classified as any gas that:

A. traps visible rays and thereby promotes
global warming.

B. traps gamma rays and thereby reduces global
warming.

C. traps infrared rays and thereby promotes
global warming.

D. traps infrared rays and thereby reduces
global warming.

Answer is C!