Ocean (and atmosphere) dynamics of the Earth are typically described at the surf
ID: 801620 • Letter: O
Question
Ocean (and atmosphere) dynamics of the Earth are typically described at the surface of a rotating sphere with a radius of 6371 km. The coordinate system thus consists of a spherical grid with fixed orientation relative to the rotation axis. The grid lines are named longitudes and latitudes. The horizontal direction or motion along longitudes (y-axis) is called meridional (positive northward). Along latitudes (x-axis) it is called zonal (positive eastward). A great circle is the largest circle one can draw aroudn a sphere.
How long is the great circle of the Earth? How is the nautical mile related to that great circle? Hwo long does the Pacific Ocean stretch out along the latitude? How does this distance compare with the mean depth of the Pacific Ocean?
Explanation / Answer
The great circle is the largest circle that can be drawn on the globe and it is the equator which is around 24,901 miles or 40,075 kilometers.
One of the most important concepts in understanding the nautical mile though is its relation to latitude. Because a nautical mile is based on Earth’s circumference, an easy way to understand the calculation of a nautical mile is to imagine the Earth being cut in half. Once cut, the circle of the half can be divided into equal portions of 360°. These degrees can then be divided into 60 minutes. One of these minutes (or minutes of arc as they are called in navigation) along a great circle on Earth represents one nautical mile. Hence the nautical mile is related as when the great circle is divided the northern and southern hemisphere can be cut into halves to understand the distance.
Pacific reaches its greatest east-west width at about 5°N latitude.
The ocean ranges in depth from 0 to more than 36,000 feet deep. The average depth of the ocean is about 12,100 feet, which is more than 2 miles! The deepest known point in the ocean is more than 7 miles below the ocean surface.The ocean's deepest area is the Mariana Trench (also called the Marianas Trench), which is about 11 km (almost 7 miles, or almost 36,000 feet) deep. The trench is 1,554 miles long and 44 miles wide, and is like the Grand Canyon of the ocean, although it is 120 times larger. Contrary to what you might picture, the trench is wide - according to NOAA, almost 5 times wider than it is deep. The Mariana Trench is located in the western North Pacific Ocean.
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