首页
登录
职称英语
What is the main topic of the passage? [originaltext] What makes it rain? Ra
What is the main topic of the passage? [originaltext] What makes it rain? Ra
游客
2023-11-06
79
管理
问题
What is the main topic of the passage?
What makes it rain? Rain falls from clouds for the same reason anything falls to Earth. The Earth’s gravity pulls it. But every cloud is made of water droplets or ice crystals. Why doesn’t rain or snow fall constantly from all clouds? The droplets or ice crystals in clouds are exceedingly small. The effect of gravity on them is minute. Air currents move and lift droplets so that the net downward displacement is zero, even though the droplets are in constant motion.
Droplets and ice crystals behave somewhat like dust in the air made visible in a shaft of sunlight. To the casual observer, dust seems to act in a totally random fashion, moving about chaotically without fixed direction. But in fact dust particles are much larger than water droplets and they finally fall. The cloud droplet of average size is only 1/2, 500 inch in diameter. It is so small that it would take sixteen hours to fall a mile in perfectly still air, and it does not fall out of moving air at all. Only when the droplet grows to a diameter of 1/125 inch or larger can it fall from the cloud. The average raindrop contains a million times as much water as a tiny cloud droplet. The growth of a cloud droplet to a size large enough to fall out is the cause of rain and other forms of precipitation. This important growth process is called "coalescence".
选项
A、The mechanics of rain.
B、The climate of North America.
C、How gravity affects air current.
D、Types of clouds.
答案
A
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3162653.html
相关试题推荐
Wheredidthestormsfirststrike?[originaltext]About100peoplearenowk
Wheredidthedivergonemissing?[br][originaltext]Adiverhasgonemissi
WheredoesObamamakethespeech?[br][originaltext]PresidentObamahasma
WheredoesObamamakethespeech?[originaltext]PresidentObamahasmarkedt
Whatdoesnothappeninthebrainintheactivesleep?[br][originaltext]E
WhatisBertrandRussell’sthirdpassion?[br][originaltext]BertrandRus
WhatisBertrandRussell’sthirdpassion?[originaltext]BertrandRussellw
Whatisthespeaker’smainlydiscussing?[br][originaltext]Alotofpeop
Whatisthespeaker’smainlydiscussing?[originaltext]Alotofpeoplethi
WhereisJoan’sfamilygoingtospendsummer?[br][originaltext]W:Charles,I
随机试题
Womenareonthevergeofoutnumberingmenintheworkforceforthefirstti
Thefieldofmedicinehasalwaysattracteditsshareofquacksandcharlatan
Parenthoodshouldbeaffordableinthiscountry,butthecostofraisingach
超声回弹综合法检测结构混凝土抗压强度,请回答以下相关问题。2)如表所示,如检测路
女性,35岁,昨晚突发尿频,尿急和尿痛,伴下腹疼痛首先考虑的检查是A.C.T
下列各项中,不符合内部牵制的要求的是()。A、出纳人员管票据 B、出纳人员
影响资本积累的主要因素的有( )。A.对劳动力的剥削程度 B.社会劳动生产率
(2018年真题)中国证监会及其派出机构对经营机构履行适当性义务进行监督管理。
(2018年真题)根据《建筑工程施工质量验收统一标准》,分项工程应按( )划分。
最新回复
(
0
)