Quick questions on Atmosphere and the global heat budget - SQA Higher Geography

Warm currents such as the North Atlantic Drift (the extension of the Gulf Stream) carry tropical heat polewards, keeping north-west Europe milder than its latitude suggests: Lerwick in Shetland (about $60$ degrees N) stays well above freezing in winter while places at the same latitude in Canada are far colder. Cold currents such as the Canary and Benguela currents return cooler water towards the Equator, completing the loop.

Scotland sits at the same latitude as Labrador in Canada, yet its west coast rarely freezes hard in winter. The reason is the North Atlantic Drift, a warm surface current carrying water from the Gulf of Mexico across the Atlantic. As the prevailing south-westerly winds blow over this warm water they pick up heat and moisture, so places such as Tiree and Stornoway have mild, wet winters.

The Sahel, the semi-arid belt south of the Sahara, depends entirely on the ITCZ. When it migrates north in the northern summer, convectional rain falls; when it stays south, drought follows. In years when the ITCZ failed to move far enough north, such as during the major Sahel droughts of the 1970s and 1980s, rainfall collapsed and famine resulted.

Explain why low latitudes receive a surplus of energy and high latitudes a deficit. [4 marks]

Explain the role of ocean currents in the redistribution of global energy. [3 marks]

Describe the movement of the ITCZ through the year and explain one effect it has. [4 marks]