EVS 1101 - Chapter 5

What was the composition of the primitive Earth's atmosphere?

N2, H2O, CO2, with some NH3 and CH4.

What event marked the significant increase of O2 in Earth's atmosphere?

The Great Oxygenation event, initiated by cyanobacteria around 2.7 billion years ago.

What is the primary equation for photosynthesis?

6CO2 + 6H2O → C6H12O6 + 6O2.

What gases make up 99.96% of the current dry atmosphere?

N2, O2, and Ar.

What is the natural greenhouse effect?

Absorption of terrestrial radiation by gases like CO2, H2O, and CH4, warming the Earth's surface.

How high can the troposphere reach?

6-18 km, greatest in the tropics.

What is the role of ozone in the stratosphere?

Ozone absorbs UV radiation, protecting life on Earth.

How is the thickness of the ozone layer measured?

In Dobson Units (DU), where 100 DU = 1 mm thick at ground level.

What happens to temperature in the mesosphere as altitude increases?

Temperature decreases with increasing altitude.

What is the thermosphere characterized by?

Rapid temperature increase due to solar particle ionization.

What is the difference between climate and weather?

Climate is the long-term view of weather patterns; weather is the current atmospheric conditions.

How does solar energy affect temperature distribution on Earth?

Sunlight strikes the poles at a shallow angle, diffusing energy, while near the equator it strikes steeply, delivering more heat.

What are the three main climate zones based on latitude?

Tropical, Mid-latitude, and Polar.

What drives atmospheric circulation?

Solar energy warms air, creating convection cells.

What are the three types of prevailing winds?

Trade winds, Westerlies, and Polar easterlies.

What is the El Niño Southern Oscillation (ENSO)?

Climate patterns in the Pacific Ocean that affect global weather.

What occurs during an El Niño event?

Trade winds weaken, warm water is pushed east, stopping upwelling.

What are the effects of La Niña on marine life?

Increased upwelling leads to more nutrients and higher bioproductivity.

What has been the trend in CO2 levels since the industrial revolution?

Increased from 278 ppm to 429.95 ppm, with 60% of the increase since 1958.

What is the role of forests in the CO2 budget?

Forests absorb CO2, but deforestation can lead to increased atmospheric CO2 levels.

What is the impact of ocean acidity on marine organisms?

Increased acidity reduces available carbonates, threatening marine life.

What is the main cause of stratospheric ozone depletion?

Chlorine and bromine compounds, particularly chlorofluorocarbons (CFCs).

What was the effect of the Montreal Protocol?

Global production of ozone-depleting substances has decreased, allowing for potential recovery of the ozone layer by 2050.

What is tropospheric ozone and its effects?

A pollutant that acts as a respiratory irritant, formed by photochemical reactions.

What is the expected change in ocean pH by 2100 if CO2 levels continue to rise?

Predicted to decrease by 170% compared to 1850.