Why clouds are the missing piece in the climate change puzzle

How much our world will warm this century depends on the actions we take in coming decades. In order to keep global temperature rise below 1.5°C and avoid dangerous levels of warming, governments need to know how much carbon ...

Has Earth's oxygen rusted the Moon for billions of years?

To the surprise of many planetary scientists, the oxidized iron mineral hematite has been discovered at high latitudes on the Moon, according to a study published today in Science Advances led by Shuai Li, assistant researcher ...

How cold was the ice age? Researchers now know

A University of Arizona-led team has nailed down the temperature of the last ice age—the Last Glacial Maximum of 20,000 years ago—to about 46 degrees Fahrenheit (7.8 C).

Experts reveal major holes in international ozone treaty

A new paper, co-authored by a University of Sussex scientist, has revealed major holes in an international treaty designed to help repair the ozone layer, putting human health at risk and increasing the speed of climate change.

Cluster's 20 years of studying Earth's magnetosphere

Despite a nominal lifetime of two years, ESA's Cluster is now entering its third decade in space. This unique four-spacecraft mission has been revealing the secrets of Earth's magnetic environment since 2000 and, with 20 ...

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Latitude

In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees (marked with °). The equator has a latitude of 0°, the North pole has a latitude of 90° north (written 90° N or +90°), and the South pole has a latitude of 90° south (written 90° S or −90°). Together, latitude and longitude can be used as a geographic coordinate system to specify any location on the globe.

Curves of constant latitude on the Earth (running east-west) are referred to as lines of latitude, or parallels. Each line of latitude is actually a circle on the Earth parallel to the equator, and for this reason lines of latitude are also known as circles of latitude. In spherical geometry, lines of latitude are examples of circles of a sphere, with the equator being a great circle.

Latitude (usually denoted by the Greek letter phi (φ)) is often measured in degrees, minutes and seconds. The Eiffel Tower has a latitude of 48° 51′ 29″ N-- that is, 48 degrees plus 51 minutes plus 29 seconds. Or latitude may be measured entirely in degrees, e.g. 48.85806° N.

If the Earth were actually spherical, and homogenous, and not rotating, then latitude at a point would just be the angle between a vertical line at that point and the plane of the equator. Everywhere on Earth a vertical line would point to the center of the Earth. In reality the earth is rotating and is not spherical, so a vertical line — a line in the direction of apparent gravity — doesn't point to the center of the Earth (except at the poles and the equator). If the Earth were homogenous, then a vertical line would still point to some point on the Earth's axis, and latitude at a point would still be the angle between the vertical line there and the plane of the equator.

But the Earth is not homogenous, and has mountains-- which have gravity and so can shift the vertical line away from the Earth's axis. The vertical line still intersects the plane of the equator at some angle; that angle is astronomical latitude, the latitude you would calculate from star observations. The latitude shown on maps and GPS devices is the angle between a not-quite-vertical line through the point and the plane of the equator; the not-quite-vertical line is perpendicular to the surface of the spheroid chosen to approximate the Earth's sea-level surface, rather than perpendicular to the sea-level surface itself.

This text uses material from Wikipedia, licensed under CC BY-SA