Exercises: The atmosphere

Name the layers of the atmosphere in order from Earth's surface outwards into space and state a characteristic feature of each.

State the main composition of air (the two dominant gases with their approximate proportions) and name two trace gases whose variation is of major environmental importance.

In which layer of the atmosphere do weather phenomena occur and in which is ozone concentrated? Explain the function of each of these two layers.

Explain what the lapse rate (vertical thermal gradient) of the troposphere is and what a thermal inversion is, relating the latter to episodes of trapped pollution over major cities in winter.

Describe the function of the stratospheric ozone layer, what substances destroyed it (CFCs), and why the Montreal Protocol is considered the greatest success of environmental diplomacy.

Outline in words the general circulation of the atmosphere (Hadley cell, Intertropical Convergence Zone, subtropical anticyclones) and use it to explain the climatic contrast between the humid north and the arid south-east of the Iberian Peninsula.

Based on the thermal profile recorded by a probe in the Earth's atmosphere (zones 1 to 4):

1. a) Justify, using the concepts of air density and lapse rate, why zone 2 acts as a dynamic lid that prevents the vertical development of storm clouds from zone 1.
2. b) Predict how the morphology of the thermal curve in zone 2 would change if the ozone layer were completely destroyed, and what direct consequence that change would have on the altitude of the upper boundary of zone 1.
3. c) Commercial flights frequently choose the transition level between zones 1 and 2, whereas auroras are only observed in zone 4. Justify the commercial flight altitude based on atmospheric stability and fuel consumption, and explain why auroras cannot occur at lower altitudes.

Consider Earth's radiation budget in initial equilibrium (average incident $340\ \text{W/m}^2$ at the top of the atmosphere).

1. a) A climate model evaluates two independent anthropogenic disturbances: 1) a reduction in mean albedo from $30\ \%$ to $28\ \%$ due to Arctic ice melt and urbanization; 2) an increase in greenhouse gases that decreases the outgoing longwave radiation emitted to outer space by $3.5\ \text{W/m}^2$. Calculate the net radiative forcing introduced by each disturbance and interpret which one would cause a greater initial thermal imbalance.
2. b) A climate change denier argues: "If Earth absorbs more energy than it emits, the surface will immediately emit more infrared radiation into space and equilibrium will be restored without an increase in mean temperature." Reasonably refute this claim using the Stefan-Boltzmann law and the absorption/re-emission mechanism of the greenhouse effect.
3. c) Explain how radiometers aboard satellites (such as the CERES mission) manage to measure Earth's energy imbalance by distinguishing reflected shortwave energy from emitted thermal longwave radiation.

Mexico City suffers from winter episodes of high pollution caused by $\text{NO}_2$ and particulates. Analyze which meteorological conditions favor them, what emergency measures are activated, and what structural solutions would reduce their frequency.