Geography Reference
In-Depth Information
surfaces during the day and they are warmer than land surfaces at
night. The same is true in the high latitudes but in the winter half-
year the temperature of the snow-covered land may remain colder
than sea surface temperatures during both day and night. Differ-
ences in local temperature across land and water result in sea and
land breezes. These breezes can also develop where there are large
inland bodies of water such as the Great Lakes in North America
or Lake Victoria in Africa.
Sea breezes only form when there are light wind conditions
during typically anticyclonic conditions. The sea breeze can exist
from the surface to 2 kilometres above ground and even up to 100
kilometres inland and brings cooler, more humid air inland. These
breezes can bring welcome relief in the tropics providing a fresher
feel to the climate of the coastal areas. When the more humid air
begins to warm over land it can start to rise forming clouds, which
is why on some summer days it can be a cloudless day inland, but
when you reach the coast it can be disappointingly cloudy. Sea
breezes die off as night falls and are sometimes replaced by a weak
land breeze blowing out to sea.
Vegetation and climate
If the land is bare then the air temperature can be affected by the
darkness of the soil and the moisture content. Darker soils absorb
more of the Sun's energy and therefore radiate more long-wave
energy back into the atmosphere to warm it from below. Moist
soils will facilitate more evaporation thereby cooling the atmo-
sphere as energy is used to evaporate the water.
The effects of vegetated surfaces on local climate are complex.
There can be large differences from forest to grassland and from
field to field depending on the crop. Different plants reflect more
or less of the Sun's energy into space. Wind speeds can be affected
by the height and density of vegetation. In fact, humans often plant
hedgerows or rows of trees where they require some shelter from
the wind. Often temperatures are warmest during the day near the
top layer of vegetation if that catches most of the Sun's energy.
The vegetation acts rather like the ground surface and absorbs
short-wave energy and releases long-wave energy to heat the
atmosphere. Also, the very top of the plant canopy will not be the
