Geology, ecosystems, land systems, and the forces shaping our planet.
VDatum is NOAA software that converts elevation data from one reference surface, or datum, to another. The transformation allows soundings, land surveys and tidal heights to line up within a common vertical framework, which is essential where a small height difference can move a mapped shoreline by many feet. NOAA’s introduction to VDatum and coastal…
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El Niño and La Niña are opposite phases of a recurring climate pattern in the tropical Pacific Ocean. El Niño features unusually warm surface water in the central or eastern equatorial Pacific. La Niña features unusually cool water in the same broad region. Both phases reorganize tropical winds and rainfall. NOAA’s comparison of El Niño…
Longitude describes a place’s angular position east or west of a chosen reference meridian. Its lines run from pole to pole, forming half-circles that meet at both ends. Combined with latitude, longitude identifies a horizontal position on Earth. NOAA’s guide to longitude and meridians explains why the zero line passes through Greenwich, England. Unlike the…
Latitude tells how far north or south a place lies on Earth. It is an angle measured from the equatorial plane, not a mileage read directly along the ground. A latitude can identify an entire east-west line, so a second coordinate is needed to locate one point. On maps and globes, latitude appears as a…
