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Metr 101-02 – Fall 2009 Lab #1 Latitude, Longitude, & Time Zones Due Tuesday 9/1/09 (40 points total) Name: ________________________________________________________ Introduction We will use this lab session to become acquainted with the concepts of latitude, longitude, and time zones. Task #1: Latitude and Longitude Latitude: is the angular distance of any point on the surface of the earth north or south of the equator. The equator is latitude 0°, and the North Pole and South Pole are latitudes 90°N and 90°S, respectively. The length of one degree of latitude averages about 69 mi (110 km); it increases slightly from the equator to the poles as a result of the earth's polar flattening. Latitude is commonly determined by means of a sextant or other instrument that measures the angle between the horizon and the sun or another celestial body, such as the North Star. The latitude is then found by means of tables that give the position of the sun and other bodies for that date and hour. An imaginary line on the earth's surface connecting all points equidistant from the equator (and thus at the same latitude) is called a parallel of latitude. On most globes and maps parallels are usually shown in multiples of 5°. Because of their special meanings, four fractional parallels are also shown. These are the Tropic of Cancer (23 1/2°N) and the Tropic of Capricorn (23 1/2°S), marking the farthest points north and south of the equator where the sun's rays fall vertically, and the Arctic Circle (66 1/2°N) and the Antarctic Circle (66 1/2°S), marking the farthest points north and south of the equator where the sun appears above the horizon each day of the year. Generally speaking, what we know as the tropics is the area of the world located between the tropics of Cancer and Capricorn and the polar regions are bounded by the Arctic and Antarctic circles. Another way of describing the different latitudes is by referring to the high latitudes in either hemisphere as being higher than 60, the middle latitudes as being roughly between 30 and 60 and the low latitudes as being lower than 30. The equatorial region is the area within a few degrees of latitude from the equator. Longitude: is the angular distance on the earth's surface measured along any latitude line such as the equator east or west of the prime meridian. A meridian of longitude is an imaginary line on the earth's surface from pole to pole; two opposite meridians form a great circle dividing the earth into two hemispheres. By international agreement, the 1 meridian passing through the original site of the Royal Greenwich Observatory at Greenwich, England, is designated the prime meridian, and all points along it are at 0° longitude. All other points on the earth have longitudes ranging from 0° to 180°E or from 0° to 180°W. Except where it is changed to account for populated areas, the International Date Line lies along the 180° meridian. Meridians of longitude and parallels of latitude together form a grid by which any position on the earth's surface can be specified. Task 1 (16 points total) For the list of cities below, write their latitude and longitude. Try using Google Earth. Search for different locations by using the “Fly to” search bar on the upper left hand corner of the screen. The latitude and longitude are displayed just below the main image. Please round to one decimal point(ie, 49.3 N degrees North, 25.3 W). Table 1 Latitude (N or S) Longitude (E or W) San Francisco, California Denver, Colorado Chicago, Illinois Miami, Florida Paris, France Baghdad, Iraq Bangkok, Thailand Tokyo, Japan Task # 2- Time Zones Time zones: Since the earth rotates about its axis once every 24 hours and one full rotation is equal to 360 degrees of longitude, the earth moves through (360/24=15) fifteen degrees of longitude every hour. This means that you can divide the earth into 24 different wedges, each wedge being 15 degrees of longitude wide and centered at the prime meridian, 15W, 30W, 45W, etc. These wedges are known as time zones. Every location on the earth located within a time zone has the same local time. By convention, each of the 24 time zones was originally denoted by a letter of the alphabet. The letters begin with the time zone just to the east of the prime meridian and increase by one letter as you move east from there. The time zone centered at the prime meridian is known as the “Z” time zone and is occasionally referred to as “Zulu” time. The proper way of referring to the local time at the prime meridian is by using “UTC” (Universal Time Coordinates) after the time. For example, if you see “18UTC” or “18Z” that refers 2 to 6pm local time at the prime meridian (which passes through Greenwich, England) Figure 1 shows the world’s time zones as of June 2004. You will notice that the boundaries of time zones do not necessarily follow straight lines along meridians. There are many “wiggles” in the time zone boundaries that have been made to accommodate political boundaries. For instance, the European countries have decided to keep most of Europe in the same time zone, to make it easier for commerce. Some places have decided to have special time zones of their own, so there are indeed “I” and “O” time zones. All the time zones of the world are detailed in the inset shown in Figure 1. Task 2 (24 points total) For this task, calculate the local time and day of the week assuming 24 uniform time zones(15 degrees of longitude per time zone). When it is 18Z on Wednesday, the local time and day of the week is: In San Francisco, California In Denver, Colorado In Chicago, Illinois In Miami, Florida In Paris, France In Baghdad, Iraq In Bangkok, Thailand In Tokyo, Japan 3 4