The Dynamics of the Atmosphere and the Hydrosphere

Wind and ocean currents get their energy from the Sun. Using an everyday example (air moving when a radiator is turned on, or water in a heated pot), explain what happens to air or water when heated and how this movement gives rise to winds or currents.

Explain in your own words what wind is and where the energy that sets it in motion comes from.

On a summer's day, the sand on the beach burns your feet, but the seawater is much cooler. Relate this fact to the formation of the sea breeze.

The diagram shows what happens on a summer morning at the coast, with four numbered steps. Explain what happens in each of the steps labelled 1 to 4 and reason why warm air rises over the land and a sea breeze forms, blowing from the sea towards the coast.

Order the following steps in the formation of a sea breeze during the day: the cool air over the sea moves towards the coast, forming the breeze; the Sun heats the land faster than the sea; the air over the land warms up and rises; higher up, the air moves towards the sea and descends over it.

During the night, the breeze on the coast blows from the land towards the sea, the opposite of during the day. Explain why the direction of the breeze reverses.

Define what an ocean current is and cite a well-known example, stating whether it is warm or cold.

The simplified map shows two ocean currents bordering two coastlines located at the same latitude.

1. a) State where each current originates and where it is headed.
2. b) Reason which of the two locations, A or B, will have a milder and wetter climate and explain why.

Ocean currents are said to be like conveyor belts transporting heat. Explain what effect a cold current has on the climate of the coast it borders and compare it with that of a warm current.

Two locations situated at the same latitude, one on the coast and another inland, have different climates: the coastal town has milder winters and cooler summers. Explain why, taking into account that seawater heats up and cools down more slowly than land.

Look at the temperature data for three locations situated at the same latitude (43° N) and at a similar altitude:

• Location 1: Average temp. in January: 9,2 °C; Average temp. in August: 21,1 °C.

• Location 2: Average temp. in January: 2,5 °C; Average temp. in August: 28,0 °C.

• Location 3: Average temp. in January: 12,0 °C; Average temp. in August: 17,5 °C.

1. a) Calculate the thermal amplitude (temperature range) of each one and deduce, with reasoned arguments, which corresponds to a small oceanic island, which to a continental coastal city, and which to the interior of a large continental landmass.
2. b) A classmate claims that seawater warms the coast in summer and cools it in winter. Refute their claim by explaining the thermal property of water (specific heat capacity) that turns the hydrosphere into a thermal regulator for the atmosphere.

London (United Kingdom) and Calgary (Canada) are located at virtually the same latitude (around 51° N). However, the average January temperature in London is 5,5 °C (with very rare snowfall), while in Calgary it is -7,5 °C (with continuous snow for months).

1. a) Justify this marked climatic difference by analysing how general atmospheric circulation and surface ocean currents interact in the North Atlantic.
2. b) A model predicts that global warming will trigger accelerated melting in Greenland, pouring huge volumes of freshwater into the ocean. Predict and justify what effect this input would have on ocean density, the North Atlantic thermohaline circulation (AMOC), and winter temperatures in north-western Europe.