Agriculture Reference
In-Depth Information
coast of California would be an example of this type of situation. In either case the agri-
culture of the area will be profoundly affected by the temperature regimes controlled by
these ocean currents.
Likewise prevailing winds blowing from a warm area or across a warm ocean
current will cause temperatures to be higher than expected in those areas affected by
the wind and similarly for wind blowing from areas of low temperature. For winds
to have a significant effect, the winds must be prevailing, which means that they
always or almost always blow from the same direction.
Large bodies of water also have a moderating effect on the temperature of an area.
The heat capacity of water is much higher than soil, and so land generally heats and
cools faster than water. Land areas near water cool and heat slower than areas far
from large bodies of water. The Philippines is surrounded by ocean. The consequence
is that the temperature is never very cold and never very hot, usually around 358C and
because of the abundance of water the humidity is always high.
Although not a variable factor in agricultural weather, rain shadows caused by
mountains can have dramatic effects on rainfall. Wind blowing off the ocean, if it
encounters a high mountain, will be pushed up high enough to cause clouds to form
and rain to fall. As the wind passes the mountains, all the water will be removed and
the area beyond is a desert or semidesert. This happens on the coast of northwestern
United States in the states of Washington and Oregon.
8.4.2 Altitude
Altitude is a very different phenomenon. As the altitude in the troposphere increases,
the temperature decreases. Perhaps one of the most dramatic effects of increasing alti-
tude on temperature is in Kenya, which is split by the equator, and Tanzania where
Mount Kenya and Mount Kilimanjaro both have snow on them all year around even
though both mountains are very near the equator. Likewise the highlands of Kenya,
Tanzania, and Zimbabwe have relatively moderate temperatures considering their clo-
seness to the equator. In and around the capital of Zimbabwe, Harare, the temperature
gets low enough that one can see frost early in the morning during the winter months,
that is, June, July, and August. In addition temperatures are low enough to turn oranges
orange (Chapter 6). In the Philippines, which has a definite tropical climate, mountai-
nous areas, such as in the north central portion of Luzon, allow production of such cool-
weather crops as strawberries and snow peas.
Baguio, Philippines
The Philippines lies between 5
8
and 21
8
north latitude and thus most of the
country has a tropical climate. In spite of this, in the central mountains of
Luzon is a valley in an area generally referred to as Baguio, which because of
its altitude is much cooler that the remainder of the country. During the winter
months of December through February night time temperatures will approach
freezing, and occasionally it will snow. In the summer months it is also cooler
than most of the Philippines. It is cool enough that cool-weather crops such as
strawberries (Fig. 8.14) for which the valley is famous, can be successfully and
economically produced.
