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Ocean Drifters Investigating Ocean Currents
Activity 1: Where On Earth Are We? Teacher
How can we find a certain place on a map or globe of the Earth?
One way is to use latitude and longitude. These words refer to a
system that helps us locate places on the Earth.
|What is latitude?
Latitude is a way to measure the distance north or south of
the Earths Equator. The lines of latitude are parallel
to the Equator. The Equator is at 0 degrees latitude (0°).
The North Pole is at 90 degrees north (90°N). The South
Pole is at 90 degrees south (90°S). Lines of latitude can
be called "parallels." as in "the 45th
|What is longitude?
Longitude is a way to measure the east-west distance on Earth.
It is measured from zero longitude, also called the Prime Meridian.
The Prime Meridian passes through the North Pole, the South
Pole, and Greenwich, England. The other longitude lines are
measured as being either east (E) or west (W) of the Prime Meridian.
Lines of longitude can be called "meridians."
How does the system of latitude and longitude
help us find places on Earth?
Any place on the Earth can be found by showing where a latitude
line and a longitude line cross each other. However, many places
do not lie exactly on a main line of latitude and longitude. So,
degrees have to be divided into smaller units. Each degree can be
broken down into 60 smaller units, called minutes. Each minute is
made of 60 seconds.
The sign ° stands for degrees. So, if you see 45°,that
is the same as saying "45 degrees."
45° = 45 degrees
The sign stands for minutes. So, if you see 25', that is
the same as saying "25 minutes"
25' = 25 minutes
The sign " stands for seconds. So, if you see 30", that
is the same as saying "30 seconds"
30" = 30 seconds
Look at the globe. "P" stands for a specific point on
That point is found where the latitude line 40 degrees north, or
crosses the longitude line 60 degrees west, or 60°W. The latitude
measurement is always
written first, before the longitude measurement. As you can see,
the point is found at 40°N, 60°W.
Figure 1: Diagram of latitude, longitude grid on a spherical Earth
(After Charton, 1988).
Now, practice finding points on a chart. Use the YOTO
Drifter Tracking Chart.
Find these locations on the YOTO Drifter Tracking Chart.
||Where are you?
Now, practice giving locations by reading the chart. For each place
listed below, write its latitude and longitude intersection (where
the lines of latitude and longitude meet on or near the locations.)
|New Orleans, Louisiana
|The island of Martinique
|Key West, Florida
This activity was adapted from "Track a NOPP Drifter" written by
Anna C. Switzer for the NOPP-Consortium of Oceanographic Activities
for Students and Teachers (COAST). To find out more, please visit
Project NOPP Drifters and
Consortium for Oceanographic
Activities for Students and Teachers. All rights reserved.
The graphics are adapted from the above source and from "Track
a Drifter," by Anna C. Switzer, excerpted from Current: The Journal
of Marine Education, "Drifter Buoys," Volume 16, Number 1, 2000.
Copyright 2000 Current: The Journal of Marine Education. Publication
of the National Marine Educators Association (NMEA). Reprinted by
permission of the NMEA. All rights reserved. For more information
about how to subscribe to the journal and to find out more about
NMEA, please visit our website.
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