This midterm will be a 50 minute closed-book exam on Tuesday October 25 at 10:30 am. It will cover the material we've discussed in class so far: History of air pollution; natural composition of the atmosphere (radiation; evolution of the Earth's atmosphere; temperature, pressure and density structure of the atmosphere); sources, transport and chemistry of pollutants; urban smog. You will find below a description of what you should know for each of these topics. The format of the exam will be similar to the format of the two homework assignments. Please bring a calculator to class.
Define air pollution. Be able to
briefly describe the five main air pollution problems.
Explain the history of air
pollution and its co-evolution with human population.
Be able to define, atoms,
molecules, particles, concentrations and mixing ratios.
Understand the difference between
concentrations and mixing ratios.
2) The natural composition of the atmosphere
A) Radiation of the Sun and the EarthUnderstand qualitatively the relationship between the wavelength of radiation, the frequency of radiation, and the energy of radiation.
Example: Rank in order of decreasing wavelength, energy, and temperature: x-rays, ultraviolet (UV), visible, and infrared (IR) radiation.
Radiation spectrum of emission from the sun and the Earth.
Understand quantitatively Wien’s Law and the Stefan Boltzmann Law.Be able to name the main greenhouse gases in the Earth’s atmosphere and describe how they influence the temperature of the Earth’s surface.
Define albedo and name the main factors that contribute to the Earth’s albedo.
B) Evolution of the Earth’s AtmosphereWhat is the approximate age of the Earth?
Where on Earth did the first organisms evolved and why?
Know the equation for photosynthesis.Why was the buildup of molecular oxygen (O2) initially slow after the start of oxygen producing photosynthesis on Earth?
How did the formation of the stratospheric ozone (O3) layer influence life on Earth?
C) Temperature, Pressure and Density Structure of the Atmosphere
Be able to describe how temperature, pressure and density vary with height.
What are the differences between the troposphere, stratosphere, mesosphere, and thermosphere? Explain the reasons for the temperature variations with altitude in the troposphere and stratosphere.
Know the ideal gas law (equation of state). Be able to calculate, for example, the temperature of a specific number of moles of a gas given the pressure and volume.
Understand quantitatively Dalton’s law of partial pressure.
D) Composition of the Present Day Atmosphere
Be able to name the major gaseous constituents of the Earth’s atmosphere.
Give examples of variable gases that influence climate, human health, and ecosystem health.Explain why ozone (O3) is either “good” or “bad” depending on where it is located in the atmosphere.
3) Sources
and fate of pollutants
Be able to describe how air
pollution is affected by transport processes in the atmosphere.
Explain why air expands as it
rises and why it cools as it rises.
Define lapse rate. What is the
dry adiabatic
lapse rate?
EXAMPLE:
Assume that the surface temperature is 10C. The atmospheric temperature
linearly decreases by increasing height until 2 km, where it reaches
0C. It then decreases with increasing height until it reaches 10C at 3
km altitude. What is the lapse rate for each of these layers?
ANSWER:
Between 0 and 2 km altitude, temperature decreases by 10C over a height
of 2 km. Lapse rate=10C/2km=5C/km.
Between 2 and 3 km altitude, temperature increases by 10C over a height
of 1 km. Lapse rate=-10C/1km=-10C/km.
Be able to diagnose the stability
of an air parcel from comparing the atmospheric lapse rate to the
adiabatic lapse rate.
Define an inversion layer.
Understand how it affects air pollution.
Describe the major atmospheric
circulation features such as the trade winds, westerlies, polar
easterlies.
Qualitatively describe the
difference between high and low pressure systems and their impact on
air pollution.
Describe three types of chemical
reactions. Be able to balance a chemical reaction.
EXAMPLE:
Fill in the blank
NO + O3 -> NO- + O2
ANSWER:
NO + O3 --> NO2 + O2
Define
residence time.
Be able to apply the box model formula to quantitatively understand the relationship between volume, residence time, source rate of a pollutant and concentration of a pollutant.
4) Urban smog
Describe the main characteristics
of photochemical smog. Understand how it differs from London-type smog.
What are the ingredients of
photochemical smog? What are their sources?
How is ozone formed in smog?
SAMPLE
QUESTION: Why is there more ozone smog during summer than during
winter?
Describe the temporal behavior of
primary and secondary pollutants in photochemical smog.
Last
Updated:
10/20/2005