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Floods can be deadly particularly when they
arrive without w {#blank#}1{#/blank#}. Yes. Usually
no signs are given before the floods. Since 2006, more than 30 people have died
as a direct result of flooding in Britain alone. Actually, it takes less rain
than you'd think to cloud your day.
Only four inches of water will ruin your
carpet(地毯) . Six inches of fast flowing water can knock you o{#blank#}2{#/blank#}your feet, and two f{#blank#}3{#/blank#}of
flood water will float your car. But where does it all come from?
Though
Britain is no stranger to bad weather at a{#blank#}4{#/blank#}time of the year，autumn is the classic time for storms. This is the time of the year
when the two factors(因素) that i{#blank#}5{#/blank#}our weather are most likely to clash(冲突) . Warm ocean currents(洋流) move up from the
Gulf of Mexico while cold air is coming down from the Arctic. When these two o{#blank#}6{#/blank#}.temperatures meet，it can cause big problems.
Low pressure develops on the border of warm
and cold air this is known as a "weather front". The air here will r{#blank#}7{#/blank#}, and as the air goes up, it cools. Any
water vapor present in the air begins to form clouds. As a result, low pressure
is generally connected with wet and windy weather.
Low pressure systems have a habit of lining
up over the north Atlantic. Like buses, sometimes one doesn't appear for ages, and
then three or more come at once. When rain starts to fall the water r{#blank#}8{#/blank#}down
from the hillsides into streams, along rivers and out into the sea. But when
rain pours for weeks at a time, the upper reaches(上游) of rivers quickly f{#blank#}9{#/blank#}land
force the excess water downstream. In the l{#blank#}10{#/blank#}reaches, water flows slower and
begins to break its banks. This is entirely common.
