A weather map is an important tool for geographers. A succession of three of four maps presents a continuous picture of weather changes. Weather forecasts are able to determine the speed of air masses and fronts; to determine whether an individual pressure area is deepening or becoming shallow and whether a front is increasing or decreasing in intensity. They are also able to determine whether an air mass is retaining its original characteristics or taking on those of the surface over which it is moving. Thus, a most significant function of the map is to reveal a synoptic picture of conditions in the atmosphere at a given time.
All students of geography should be able to interpret a weather map accurately. Weather maps contain an enormous amount of information about weather conditions existing at the time of observation over a large geographical area. They reveal in a few minutes what otherwise would take hours to describe. The United States weather Bureau issues information about approaching storms, floods, frosts, droughts, and all climatic conditions in general. Twice a month it issues a 30-day outlook which is a rough guide to weather conditions likely to occur over broad areas of the United States. These 30-day outlooks are based upon an analysis of the upper air levels with often set the stage for the development of air masses, fronts, and storms. Considerable effort is being exerted today to achieve more accurate weather predictions. With the use of electronic instruments and earth satellites, enormous gains have taken place recently in identifying and tracking storms over regions which have but few meteorological stations. Extensive experiments are also in progress for weather modification studies. But the limitations of weather modification have prevented meteorological results except in the seeding of super-cooled, upslope mountainous winds which have produced additional orographical precipitation on the windward side of mountain ranges. Nevertheless, they have provided a clearer understanding of the fundamentals of weather elements.
1 One characteristic of weather maps not mentioned by the author in this passage is .
A wind speed
B thermal changes
C fronts
D barometric pressure
2 The thirty-day forecast is determined by examining .
A upper air levels
B satellite reports
C changing fronts
D daily air maps
3 The observation of weather conditions by satellites is advantageous because it .
A gives the scientist information not obtained readily otherwise
B enables man to alter the weather
C uses electronic instruments
D is modern
4 A weather map is synoptic because it .
A summarizes a great deal of information
B can be interpreted accurately
C appears daily
D shows changing fronts
5 At the present time, experiments are being conducted in .
A 30-day outlook
B controlling storms
C satellites
D manipulating weather
参考答案
1. B2. A3. D4. A5. D
Words to Live by 2
Pattern of Success
Freeze the Design
无论何时何地学会爱你自己
My Miraculous Family
Do It Now
Feeling of Youth
抓紧时间
Selling My Mother's Dresses
苹果地图业务高管遭解雇
自由飞翔
Telephone Tips
享受过程的乐趣
Today I begin a new life 1
Loving with an Open Hand
She Left Her Shoes
The Powerful Gift of Love
Living life over
I will greet this day with love 2
Fifty-percent Expectation
在书店里度过的时光
在工作中成长
The Smile
美句欣赏
唤醒你的生活
Cost of Living 给生命定价
Celebration of Life
I am nature's greatest miracle 2
愿你的思想永远充满阳光
享受世间的苦乐悲喜
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