Ocean currents

The governing concept is the climatic effect of cold eastern boundary currents. These currents commonly move equatorward along the eastern sides of ocean basins, bringing relatively cool water from higher latitudes. Cool water reduces evaporation and limits the supply of moisture to the air; stable air above the cool surface also suppresses convection. As a result, nearby west-coast regions may experience low rainfall, although fog can occur. Option A is correct because the Canary Current affects the northwest African coast and the Benguela Current affects southwest Africa; both are cold eastern boundary currents associated with coastal aridity. The Gulf Stream, Kuroshio, Brazil, East Australian, Agulhas, and North Atlantic Drift are warm currents, so the other pairs do not fit.

The governing idea in human geography is the relationship between physical processes and human activities, settlements, economies, and environmental risks. Ocean currents redistribute heat and water, and this physical movement affects the routes and speed of ships, the location and productivity of fisheries, the transport and concentration of floating pollutants, and the climate experienced by coastal communities. These links make currents relevant to both economic geography and environmental geography. Option A is correct because it names several direct and socially important effects. Option B treats a dynamic physical process as decoration. Option C is contradicted by navigation, trade, food supply, and coastal hazards. Option D is also wrong: currents do not only form mountains and are not primarily a mountain-building process. Thus A provides the broadest and most accurate human-geographical explanation.

The governing concept is geographic proximity: an ocean current modifies the temperature and moisture of the air and surface water near the route it follows. A coastal current can warm or cool the adjacent sea, influence evaporation, alter the stability of coastal air, and affect fog, rainfall, or aridity. Winds may carry some of this modified air inland, so the effect can extend beyond the immediate shoreline, but it is normally strongest near the current and downwind coast. Option A is correct because it connects the current’s location with the spatial pattern of its climatic influence. Option B denies a well-established ocean–atmosphere relationship. Option C ignores differences in current direction, wind, relief, and exposure. Option D is physically impossible because ocean currents flow through seawater, not inside land.

The governing concept is the interaction of oceanic heat and atmospheric moisture transport. A warm current raises the temperature of nearby surface water and generally promotes evaporation, adding water vapour to the air. If winds blow from the sea toward the land, they carry this moist air over the coast. When the air rises because of relief, convergence, or convection, it cools and condensation can produce clouds and rainfall. Therefore option A is correct, although rainfall is not guaranteed because atmospheric stability and topography also matter. Option B is the opposite of the expected moisture effect and is too absolute. Option C confuses evaporation with disappearance of seawater; evaporation transfers water vapour and does not remove the ocean. Option D has no physical basis, since a current and moist wind do not stop all winds.

The governing concept is ocean-current heat transport and its effect on coastal water temperature. A warm current carries energy from lower latitudes toward colder regions. When it passes near a port, it can keep the adjacent seawater relatively warmer than the surrounding air or than water at comparable high-latitude locations. This reduces the likelihood that the harbour surface will freeze and can help maintain navigation during cold seasons. Option A is correct because it states the physical mechanism directly. Option B concerns the drying influence of cold currents, not warming of harbour water. Option C describes biological productivity caused by nutrient-rich upwelling and does not explain reduced freezing. Option D concerns floating material in a rotating current system and has no necessary connection with port temperature. The current need not make the climate warm overall; its local heat supply is sufficient to explain the effect.