首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Longitude and Latitude The meridians of longitude are imaginary great circles drawn from pole to pole around the earth. By
Longitude and Latitude The meridians of longitude are imaginary great circles drawn from pole to pole around the earth. By
admin
2013-09-28
34
问题
Longitude and Latitude
The meridians of longitude are imaginary great circles drawn from pole to pole around the earth. By international agreement, the meridian of longitude passing through Greenwich, England, is numbered zero. The earth is divided into 360 degrees, and the meridians are numbered east and west from Greenwich. There are 180 degrees of longitude east of Greenwich and 180 degrees in the westerly direction. New York has a longitude of 74 degrees west (74oW.) which means that it lies on the 74th meridian west of Greenwich.
Since the sun appears to travel around the earth in 24 hours, it will move 360/24 or 15 degrees in one hour. This reasoning can be used by navigators to determine their longitude. Imagine that we have set sail from Greenwich, England, after having set a very accurate clock, or chronometer, to the local Greenwich time. As we travel westward toward New York, we notice that the sun is going "slower" than our chronometer. At the time that our timepiece reads 12 o’clock, the sun has not quite reached the zenith. As a matter of fact, when our clock reads noon, what it really means is that it’s noon in Greenwich, England. Our clock continues to tell us the time, not at our present location, but at Greenwich. Let us wait until the sun is directly overhead (noon at our location) and then read the time on our clock. Suppose it reads i o’clock. This means that there is one hours difference in time between our longitude and that of Greenwich. As we mentioned earlier, this corresponds to exactly 15 degrees of longitude, so our longitude must be 150 W. The world is divided into 24 time zones, and each zone corresponds to 15 degrees of longitude. New York is approximately 5 time zones west of Greenwich, so the time difference must be about 5 hours. By maintaining chronometers on Greenwich time, ships can determine their longitude on any sunny day by merely noting the difference in hours between Greenwich time and local sun time and multiplying this difference by 15 degrees.
Of course, longitude gives only half of the information needed to determine our precise location. We must also know our latitude, which tells us how far we are north or south of the Equator. The Equator is the zero line for the measurement of latitude. Circles are drawn parallel to the Equator to indicate other values of latitude. There are 90 degrees of south latitude.
In the Northern Hemisphere there is a star called Polaris almost directly over the North Pole. This makes it possible to determine the latitude of a given point by setting our sextant (六分仪) to measure the angle between Polaris;the North Star, and the horizon. Mathematicians tell us that this angle is equal to the latitude at the point in question.
To get idea of our location, therefore, we need to know local time, Greenwich time, and the angle between Polaris and the horizon.
A navigator’s chronometer will always show _____________.
选项
A、Greenwich time
B、noon time
C、local time
D、sun time
答案
A
解析
转载请注明原文地址:https://jikaoti.com/ti/JAJMFFFM
0
专业英语四级
相关试题推荐
Theearthquakeof26thDecember2004resultedinoneoftheworstnaturaldisastersinlivingmemory.Itwasa【C1】______underwa
WhichofthefollowingstatementsisCORRECTaboutMary?
Accordingtothepassage,theworkof"YouthSummit"refersto
Whichofthefollowingistheauthor’smainpurposeinwritingthepassage?WhichofthefollowingisNOTincludedinDr.Eliot
Whichofthefollowingistheauthor’smainpurposeinwritingthepassage?Beforethechange,Harvard______.
I’msorryIcouldn’tmakecontactwithhimbeforeIleft.I______earlier.
Thesestudentsdon’trealize______tostartandrunacompanyupongraduation.
OrganicAgricultureTheideathatshoppingisthenewpoliticsiscertainlyenticing.Nevermindtheballotbox:votewithy
Diamondshavelittle______valueandtheirpricedependsalmostentirelyontheirscarcity.
______Ihatetodoit,Imuststayhomeandstudytonight.
随机试题
女,30岁。外伤致肱骨中下1/3骨折,伴有桡神经损伤,临床上除骨折体征外,还可出现的体征是()
在公共政策分析中应用最广泛而又最缺乏理论色彩的决策模型是()
固冲汤是由哪几方面药物组成的
《夏书》中记载的“墨”罪意思是()。
《中华人民共和国港口法》(2003年6月28日第十届全国人民代表大会常务委员会第三次会议通过)第七条规定编制港口规划应当组织()论证。
(2004年考试真题)下列各项中,不影响企业营业利润的有()。
甲公司为增值税一般纳税人,适用的增值税税率为13%。2021年3月发生与职工薪酬有关的交易或事项如下:(1)对行政管理部门使用的设备进行日常维修,应付企业内部维修人员工资12万元;对销售部门使用的设备进行日常维修,应付企业内部维修人员工资10万元
老王和老赵分别参加4门培训课的考试,两人的平均分数分别为82和90分,单个人的每门成绩都为整数且彼此不相等。其中老王成绩最高的一门和老赵成绩最低的一门课分数相同,问老赵成绩最高的一门课最多比老王成绩最低的一门课高多少分?()
试析中古社会门阀政治的形成和衰落的主要原因。
Manyoftheactivitiesperformedduringthepreliminaryinvestigationarestillbeingconductedin(71),butinmuchgreaterde
最新回复
(
0
)