Question

1. What causes MOST of the ocean currents on the surface of the ocean?

2. England is part of an island surrounded by ocean water.Why are temperatures mild in the winter and cooler in the summer than other countries, not surrounded by water? Explain your answer.

Answer 1

An ocean current is a continuous, directed movement of seawater generated by forces acting upon this mean flow, such as breaking waves, wind, the Coriolis effect, cabbeling, and temperature and salinity differences, while tides are caused by the gravitational pull of the Sun and Moon. Depth contours, shoreline configurations, and interactions with other currents influence a current's direction and strength.

Ocean currents flow for great distances, and together, create the global conveyor belt which plays a dominant role in determining the climate of many of the Earth’s regions. More specifically, as ocean currents influence the temperature of the regions through which they travel, warm currents increase the temperature of the coasts along which they move and sea breezes that blow over warm currents are in turn warmed and absorb moisture. Perhaps the most striking example is the Gulf Stream, which makes northwest Europe much more temperate than any other region at the same latitude. Another example is Lima, Peru where the climate is cooler (sub-tropical) than the tropical latitudes in which the area is located, due to the effect of the Humboldt Current.

Answer 2

1) The wind (the prevailing wind)
2) The sea takes a lot longer to warm up than the land and so does not get to its warmest until late autumn in the UK, once it has had the entire summer to get warmer. However, once the sea does warm it it stays warm for a lot longer than the land does as the land losses heat a lot more quickly. This means that in the winter when the land has lost its heat the sea is still warm and so warms the land it is in contact with (not just the very edges, quite far into the landmass is warmed even if only slightly). As the UK is an island a high proportion of its landmass is located fairly close to the sea so will be warmed during the winter. This causes the UK to be slightly warmer in the winter than countries which are not surrounded by water as the land of these countries will lose heat just as fast but not be warmed by the seas retained heat.