1 The effect of the oceans on climate

Figure 1

This map is centred on the north Atlantic Ocean, showing ocean temperature, with blue representing colder temperature and red representing hotter temperature.

The map covers the area from the north of Greenland to North Africa and from the Great Lakes in North America to the east of the Mediterranean Sea.

Two cities are indicated on the map; Halifax, Nova Scotia in Canada and Bergen, in Norway.

There is no scale on the map but the longitude and latitude are marked and there are dotted black grid lines at the marked longitudes and latitudes.

Along the lower horizontal edge of the map, longitude is marked, from 90° W to 30° E in 20° intervals of even size.

Along the left vertical edge of the map, latitude is marked from 30° N to 80° N, in 10° intervals that are not even in size. The size of each 10° interval increases as you move north.

The key for ocean colour is provided in a horizontal bar below the map. It is labelled 'sea surface temperature/°C' and it is marked from −2° to 30° in 2° intervals. The colour changes from dark blue at −2°, through increasingly paler shades of blue to 12°. The colour then changes to yellow at 14° and the progresses through increasingly darker shades of orange to 20°,and then through increasingly darker shades of red to dark red at 30°.

The general pattern of temperature change seen is one of increasing temperature as you move from north to south, with dark blue colour dominating the waters to the east and west of Greenland and the orange /red colours restricted to a narrow band at the very south of the map.

There is also clear east west pattern noticeable and the colder temperatures extend much further south along the west side of the Atlantic, with a finger of the coldest water marked extending down as far south as Newfoundland in Canada.

The warmest temperatures maintain a more or less horizontal patterns across the Atlantic, but the contours for temperatures in the 4° to 12° range extend much further north along the east side of the Atlantic and there is a finger of paler blue protruding north along the coast of northern Scandinavia.

Figure 2

This line graph shows the change in mean atmospheric temperature during a year for Halifax and Bergen.

The horizontal axis is labelled 'month' and is marked from Jan to Dec in monthly intervals.

The vertical axis is labelled 'temperature/°C' and is marked from −10 to 20 in intervals of 5 °C.

There are horizontal and vertical gridlines at the axes markers.

There are two lines on the graph representing the temperature: The temperature at Bergen is presented with a blue line and the temperature for Halifax is presented with a red line.

The temperature at Bergen shows a shallow inverted 'U' shape with low temperatures in the winter months at either end of the graph and high temperatures in the summer months in the middle of the graph. The temperature starts at approximately 0° in Jan and rises steadily through 5° (Apr) to a peak of 14° (July) and then decreases steadily to 2° (Dec).

The temperature at Halifax shows a more extended inverted 'U' shape with lower temperatures in the winter months at either end of the graph and higher temperatures in the summer months in the middle of the graph. The temperature starts at approximately −6° in Jan and Feb and then rises rapidly through 5° (Apr) to a peak of 18° (July) and then decreases steadily to −4° (Dec).