Weather is created by the heat of the sun. When the sun shines on the earth, the air close to the surface heats up, expands, and rises. The higher it goes, the cooler it becomes. Meanwhile, an area of warmer with low-pressure air forms below it. Winds are caused by the air moving from an area of high pressure to one of low pressure. The closer the pressure centers are to each other, and the greater the pressure difference between them, the stronger the wind will be.
High- and low- pressure air masses travel the globe and cause major weather changes. When a cold, high- pressure polar air mass meets an extremely low-pressure tropical air mass, their combination can produce intense storms such as typhoons, hurricanes, and tornados. Less severe weather conditions are often caused by small, local pressure areas. A mild rain storm occurs when rising warm air combines with cool air. Clouds are created as the moist warm air cools and condenses to form water droplets. When clouds reach a saturation point, or the point at which they can no longer contain their moisture, the droplets fall to earth as rain or snow.
Weather forecasters look as the movement of warm and cold air masses and try to predict how they will behave. Although weather forecasting is not completely accurate, satellites, sophisticated instruments and computers make weather prediction far more accurate today than in the past. The advantages of weather prediction are numerous, but in the end, nature does whatever it pleases. We may attempt to predict weather but we cannot control it.
Reference Question:
What does “it” in line 3 refer to?
What does “them” in line 6 refer to?
What does “their” in line 13 refer to?
Vocabulary Question:
What do you think the word “intense” in line 9 means? Find another word with a similar meaning in the sentences near it.
What happens when air “condenses” according to line 12? What do you think “condenses” means here?
What does “saturation point” in line 13 mean? Where in the passage is the meaning of the saturation point given?
What do you think “sophisticated instruments” in line 17 means? Give two examples of sophisticated instruments that you know.
(Extract from Reading Comprehension, Compiled by OM Soryong, Institute of Foreign Languages (IFL), Phnom Penh, p.11-12)
