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.