SNOW-MAKERS
Skiing is big business nowadays. But what
can ski resort owners do if the snow doesn’t come?
A. In
the early to mid-twentieth century, with the growing popularity of skiing, ski
slopes became extremely profitable businesses. But ski resort owners were
completely dependent on the weather: if it didn’t snow, or didn’t snow enough,
they had to close everything down. Fortunately, a device called the snow gun
can now provide snow whenever it is needed. These days such machines are
standard equipment in the vast majority of ski resorts around the world, making
it possible for many resorts to stay open four months or more a year.
B. Snow
formed by natural weather systems comes from water vapour in the atmosphere.
The water vapour condenses into droplets, forming clouds. If the temperature is
sufficiently low, the water droplets freeze into tiny ice crystals. More water
particles then condense onto the crystal and join with it to form a snowflake.
As the snowflake grows heavier, it falls towards the Earth.
C. The
snow gun works very differently from a natural weather system, but it
accomplishes exactly the same thing. The device basically works by combining
water and air. Two different hoses are attached to the gun, one leading from a
water pumping station which pumps water up from a lake or reservoir, and the
other leading from an air compressor. When the compressed air passes through
the hose into the gun, it atomises the water-that is, it disrupts the stream so
that the water splits up into the droplets. The droplets are then blown out of
the gun and if the outside temperature is below 00C, ice crystals
will form, and will then make snowflakes in the same way as natural snow.
D. Snow-makers
often talk about dry snow and wet snow. Dry snow has a relatively low amount of
water, so it is very light and powdery. This type of snow excellent for skiing
because skis glide over it easily without getting stuck in wet slush. One of
the advantages of using a snow-maker is that this powdery snow can be produced
to give the ski slopes a level surface. However, on slopes which receive heavy
use, resort owners also use denser, wet snow underneath the dry snow. Many
resorts build up the snow depth this way once or twice a year, and then
regularly coat the trails with a layer of dry snow throughout the winter.
E. The
wetness of snow is dependent on the temperature and humidity outside, as well
as the size of the water droplets launched by the gun. Snow-makers have to
adjust the proportions of water and air in their snow guns to get the perfect
snow consistency for the outdoor weather conditions. Many ski slopes now do
this with a central computer system that is connected to weather-reading
stations all over the slope.
F. But
man-made snow makes heavy demands on the environment. It takes about 275.000
litres of water to create a blanket of snow covering a 60 X 60 metre area. Most
resorts pump water from one or more reservoirs located in low-lying areas. The
run-off water from the slopes feeds back into these reservoirs, so the resort
can actually use the same water over and over again. However, considerable
amounts of energy are needed to run the large air-compressing pumps, and the
diesel engines which run them also cause air pollution.
G. Because
the expense of making snow, ski resorts have to balance the cost of running the
machines with the benefits of extending the ski season, making sure they only
make snow when it is really needed, and when it will bring the maximum amount
of profit in return for the investment. But man-made snow has a number of other
uses as well. A layer of snow keeps a lot of the Earth’s heat from escaping
into the atmosphere, so farmers often use the man-made snow to provide insulation
for winter crops. Snow-making machines have played a big part in many movie productions.
Move producers often take several months to shoot scenes that cover just a few
days. If the movie takes place in a snowy setting, the set decorators have to
get the right amount of snow for each day of shooting either by adding man-made
snow or melting natural snow. And another important application of man –made
snow is its use in the tests that aircraft must undergo in order to ensure that
they can function safety in extreme conditions.
Read the passage about snow-makers which has seven paragraphs.
Choose the correct heading for each paragraph from the list of the
headings below. Write the correct number (i-x)
List of headings
i.
Considering ecological costs
ii.
Modifications to the design of the snow gun
iii.
The need for different varieties of snow
iv.
Local concern over environmental issues
v.
A problem and a solution
vi.
Applications beyond the ski slopes
vii.
Converting wet snow to dry snow
viii.
New method for calculating modifications
ix.
Artificial process, natural product
x.
Snow formation in nature
ANSWER
1. Paragraph A …………v……………
2. Paragraph B ………………………
3. Paragraph C ………………………
4. Paragraph D ………………………
5. Paragraph E ………………………
6. Paragraph F ………………………
7. Paragraph G ………………………
Complete the sentences below.
Choose NO MORE THAN THREE WORDS
from the passage for each answer.
8. Dry
snow is used to give slopes a level surface, while wet snow is used to increase
the _______ on busy slopes.
9. To
calculate the required snow consistency the ________ and ________ of the
atmosphere must first be measured.
10. The
machinery used in the process of making the snow consumes a lot of ______ which
is damaging to the environment.
11. Artificial
snow is used in agriculture as a type of ______ for plants in cold conditions.
12. Artificial
snow may also be used in carrying our safety checks on ______________________
ANSWER KEY
1. v
2. x
3. ix
4. iii
5. viii
6. i
7. vi
8. depth
9. temperature/
humidity
10. energy
11. insulation
12. aircraft
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