What is the difference between a “mile per hour (MPH)” and a “knot”?
A mile per hour is a speed of 1 statute mile (5280 ft) per hour. A knot is a speed of 1 nautical mile (roughly 6076 ft) per hour. While MPH are generally used for wind speeds on land in public statements and forecasts, aviation and marine users normally refer to wind speeds in knots. To convert from knots to MPH, 1 knot = 1.15 MPH. A nautical mile is approximately one minute of latitude (1/60th of a degree). Hence, one degree of latitude is approximately 60 nautical miles. Although the earth is not a perfect sphere, this conversion factor is close at most latitudes. Remember that the latitude lines run parallel to the equator, while the longitude lines run from pole to pole. A distance of one degree of longitude varies depending on the latitude, as longitude lines are much closer near the poles than they are near the equator.