Geography midterm


PHYSICAL GEOGRAPHY LECTURE 4: Human Impact on the Atmosphere


1. POLLUTION- As you will see on page 77, humans create many pollutants from our energy use.

The majority of our pollution stems from our dependence on autos (accounting for 60% of pollution),

and our industrial technologies (industries account for 40% of pollution).

2. URBAN PLUME - this is the term used to describe local pollution impact. As industries and autos

pump out greater pollution local winds move these particles in predictable patterns. In California, we

are dominated by NW winds (winds from the NW) which move our pollution to the southeast

sections of our towns. Just think about Modesto, where are most of our industries located? Does this

have any relationship to the location of poor housing or the location of Dutch Hollow and Del Rio in

the northwest of Modesto?

3. URBAN HEAT ISLAND - as discussed in lecture 3, this is a temperature inversion caused by

pollution. As pollution levels increase, our communities are dominated by smog which traps LW

radiation and increases the temperature of our lower atmosphere.

4. ACID RAIN - in the 1970's Americans became frustrated with the air quality in their cities and

decided to do something about it. They passed the Clean Air Act in 1970 (p.83), which demanded

that all industries raise smokestacks to a standard of 200 feet in elevation. How did this clean the air?

Well, it allowed the smog to rise higher in the atmosphere and be moved away from the city by the

Jet Stream. In addition, pollution particles became condensation nuclei for clouds (particles which

allow hydrogen bonding, water to collect). This created acidic precipitation (see page 81-83), which

lead to deforestation, crop loss and loss of marine life in areas downwind from major industries.

5. DEFORESTATION- through time humans have used a great amount of forest products in building

and as an energy source. Since the 1970's we have seen an increasing amount of deforestation in the

U.S.A., in industrial regions by Acid Rain, and a tremendous amount of rainforest loss in the

Amazon. What is important is to remember that the forests are considered the "lungs" of the Earth,

producing oxygen for ozone creation and absorbing CO2. It seems obvious that as industrial

pollution has increased, we need greater amounts of vegetation to process this pollution.

6. OZONE DEPLETION - as you read the focus study regarding ozone depletion, please recognize

the major causes of O3 depletion, and the effect it will have upon the earth, not just humans. Be sure

to watch the video about Ozone formation---this will help you understand the process and

vulnerability of ozone.

7. GLOBAL WARMING - on page 66, you will see a graph which measures air temperatures since

the 1880's. This graph illustrates the change in air temperatures since early industrialization. The

measurement of global warming has been an issue of debate since the 1970's.

I want you to think about how the earth attempts to balance increasing heat if global warming is

occurring. How does the earth create an energy equilibrium if we are increasing the retention of LW

radiation? As you read lecture 4 and chapter 5, think about the role of the oceans in maintaining a

temperature equilibrium. If global warming is occurring, the earth would look to water reserves at the

poles (ice cores). Once melted, the volume of water on the planet would increase and this would

enable the earth to not heat as rapidly (taking water longer to heat than land). Of course, it would

make much beachfront property worthless (projected to flood areas less than 200 feet in elevation---

hey, what's the elevation of Modesto?!) and flood areas of low elevation.

* The key to understanding each of these problems is to see that humans can alter the surface

of the earth (changing albedo and the amount of insolation or SW absorbed) and we can also

alter the atmosphere's composition (changing the amount of LW released).


1. VEGETATION - plant a tree, this will stimulate photosynthesis, carbon storage and ozone

creation! This can also alter albedo, increasing the albedo (as compared to asphalt) in order to reduce

the amount of SW absorbed.

2. LIMIT POLLUTION- reduce emissions, alternative energies, alternative transportation, reduce

use of aerosols

3. What are YOUR ideas?