Exercises: Structure and dynamics

Order the layers of the atmosphere starting from the Earth's surface and state in which one weather occurs and in which the ozone layer is concentrated.

What is the difference between weather and climate? Give an example of a meteorological data point and one of a climate data point.

Why is the atmosphere essential for life? State at least three functions it performs.

Name the three main gases of dry air and their approximate proportions, and name two trace gases of great climatic importance.

What is atmospheric pressure and how does it vary with altitude? Why is it harder to breathe at the summit of a four-thousand-meter peak?

What are sea breezes and land breezes? Explain at what time of day each one blows and why.

What does a rain gauge measure and what does an anemometer measure? In which units is each measurement expressed?

What is the relative humidity of the air and what happens when it reaches $100\ \%$? What is the temperature at which this occurs called?

The diagram shows the atmospheric circulation of one hemisphere with three cells (1–3) and four surface positions marked with "?". Assign each position its latitude (0°, 30°, 60°, 90°), name the three cells, and explain why high-pressure belts are located around 30°.

Surface currents in the North Atlantic form a clockwise gyre. Explain the factors that generate it (prevailing winds, Coriolis effect, arrangement of continents) and what effect the Gulf Stream has on the climate of Western Europe.

The mean vertical lapse rate of the troposphere is about $6.5\ \text{°C}$ per $1\,000\ \text{m}$. If at the coast, at sea level, the temperature is $24\ \text{°C}$, estimate the temperature at an altitude of $2\,500\ \text{m}$ and explain which physical process causes it.

The Coriolis effect deflects winds to the right in the Northern Hemisphere. Explain its cause, related to the Earth's rotation, and how it determines the direction of the trade winds and the westerlies.

Compare a cold front and a warm front: which air mass advances in each one, which clouds it generates, and what type of precipitation (intense and brief versus gentle and persistent) it brings.

In the northern hemisphere, depressions rotate counterclockwise and anticyclones clockwise. Explain the circulation of each system and the type of weather they bring to the Iberian Peninsula.

The coast of Galicia is humid and that of Morocco is much drier. Relate these differences to latitude, ocean currents, prevailing winds, and the orientation of each coastline.

What is thermohaline circulation and what drives it (differences in temperature and salinity)? Explain the role of deep currents in the global climate.

Imagine a coastal strip at 22° S on the western side of a continent. A mining company plans to discharge thermal effluents offshore that would permanently raise the sea surface temperature by +4.5 °C along 300 km of coastline.

1. a) Reasonably predict how this localized warming will affect the marine subsidence thermal inversion, the stability of the atmospheric boundary layer, and the precipitation of the adjacent coastal desert.
2. b) An environmental report states: "Since the water will be warmer, evaporation will increase and it will rain more on the inland mountain peaks, but the immediate coastline will remain just as hyper-arid because the subtropical latitude completely dictates the climate." Refute or qualify this statement using thermodynamic arguments, comparing the mechanism of a cold current with that of a warm current.

At the Darwin weather station (northern Australia), a barometric anomaly of +3.5 hPa relative to the average is recorded over several months, while pressures in Tahiti are unusually low. At the same time, along the Peruvian coast, anchoveta fishery catches collapse and satellite sensors detect trade winds that are abnormally weak or reversed.

1. a) Interpret these records within the framework of the ENSO phenomenon: deduce which phase the Walker cell is in and describe the spatial reorganization of its ascending and descending branches compared to the neutral pattern.
2. b) Explain the apparent paradox that this atmospheric alteration simultaneously causes torrential rains and flooding along the desert coast of Peru and severe droughts with wildfires in the forests of Indonesia.
3. c) Predict what will happen to the depth of the equatorial thermocline and to the slope of sea level between the eastern and western coasts of the Pacific during this event.

The thermopluviometric data of two weather stations on the Iberian Peninsula located at practically the same latitude (approx. 42.2° N) are analyzed:

• Station 1: Mean January temp. = 8.8 °C; Mean July temp. = 19.5 °C; annual temperature range = 10.7 °C. Annual precipitation = 1,250 mm.

• Station 2: Mean January temp. = 3.2 °C; Mean July temp. = 22.4 °C; annual temperature range = 19.2 °C. Annual precipitation = 410 mm.

1. a) Reasonably assign each station to either the Galician Atlantic coast or the northern Castilian plateau (Meseta Norte), basing your answer on the specific heat of water compared to that of the lithosphere and on the general westerly circulation.
2. b) Explain why the presence of intervening mountain ranges exacerbates the hygrometric and pluviometric contrast through the Föhn effect.
3. c) Predict how the annual temperature range and winter temperatures of Station 1 would change if the Earth rotated in the opposite direction (from east to west), keeping the same distribution of land and seas.

Bordeaux (France, 44.8° N) and Halifax (Canada, 44.6° N) share the same latitude on opposite sides of the North Atlantic. In January, the mean temperature in Bordeaux is +6.8 °C (it rarely snows), whereas in Halifax it is -5.5 °C (with sea ice and continuous snow).

1. a) A student states: «This difference of more than 12 °C is solely and exclusively due to the fact that the Gulf Stream warms Europe and does not reach America». Critically evaluate this statement: demonstrate why it is incomplete by integrating into your answer the direction of the westerlies and the continental or maritime nature of the air masses affecting each coast.
2. b) Explain the complementary role played by the cold Labrador Current along the North American coastline, and predict what would happen to winter temperatures in Bordeaux if a massive influx of freshwater from melting ice collapsed the North Atlantic branch of the ocean conveyor belt.
3. c) If the Eurasian landmass did not exist and the Atlantic extended eastward without barriers, how would this affect the winter climate of the European Atlantic facade? Justify your answer.