The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the Solar System as Earth's North Pole.
The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean in the south, and is bounded by the continents of Asia and Australia in the west and the Americas in the east.
A geographic coordinate system (GCS) is a spherical or geodetic coordinate system for measuring and communicating positions directly on Earth as latitude and longitude. It is the simplest, oldest and most widely used of the various spatial reference systems that are in use, and forms the basis for most others. Although latitude and longitude form a coordinate tuple like a cartesian coordinate system, the geographic coordinate system is not cartesian because the measurements are angles and are not on a planar surface.
North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. North is a noun, adjective, or adverb indicating direction or geography.
The Tropic of Capricorn is the circle of latitude that contains the subsolar point at the December solstice. It is thus the southernmost latitude where the Sun can be seen directly overhead. It also reaches 90 degrees below the horizon at solar midnight on the June Solstice. Its northern equivalent is the Tropic of Cancer.
The Western Hemisphere is the half of the planet Earth that lies west of the Prime Meridian—which crosses Greenwich, London, England—and east of the 180th meridian. The other half is called the Eastern Hemisphere. Geo-politically, the term Western Hemisphere is often used as a metonym for the Americas or the "New World", even though geographically the hemisphere also includes parts of other continents.
A circle of latitude or line of latitude on Earth is an abstract east–west small circle connecting all locations around Earth at a given latitude coordinate line.
The Southern Hemisphere is the half (hemisphere) of Earth that is south of the Equator. It contains all or parts of five continents and four oceans, as well as New Zealand and most of the Pacific Islands in Oceania. Its surface is 80.9% water, compared with 60.7% water in the Northern Hemisphere, and it contains 32.7% of Earth's land.
The Intertropical Convergence Zone, known by sailors as the doldrums or the calms because of its monotonous windless weather, is the area where the northeast and the southeast trade winds converge. It encircles Earth near the thermal equator though its specific position varies seasonally. When it lies near the geographic Equator, it is called the near-equatorial trough. Where the ITCZ is drawn into and merges with a monsoonal circulation, it is sometimes referred to as a monsoon trough.
A landmass, or land mass, is a large region or area of land that is in one piece and not broken up by oceans. The term is often used to refer to lands surrounded by an ocean or sea, such as a continent or an island. In the field of geology, a landmass is a defined section of continental crust extending above sea level.
In astronomy, the meridian is the great circle passing through the celestial poles, as well as the zenith and nadir of an observer's location. Consequently, it contains also the north and south points on the horizon, and it is perpendicular to the celestial equator and horizon. Meridians, celestial and geographical, are determined by the pencil of planes passing through the Earth's rotation axis. For a location not on this axis, there is a unique meridian plane in this axial-pencil through that location. The intersection of this plane with Earth's surface defines two geographical meridians, and the intersection of the plane with the celestial sphere is the celestial meridian for that location and time.
The Eastern Hemisphere is the half of the planet Earth which is east of the prime meridian and west of the antimeridian. It is also used to refer to Afro-Eurasia and Australia, in contrast with the Western Hemisphere, which includes mainly North and South America. The Eastern Hemisphere may also called the "Oriental Hemisphere", and may in addition be used in a cultural or geopolitical sense as a synonym for "Old World."
The 180th meridian or antimeridian is the meridian 180° both east and west of the prime meridian in a geographical coordinate system. The longitude at this line can be given as either east or west.
The 45×90 points are the four points on Earth which are both halfway between one of the geographical poles and the equator, and halfway between the Prime Meridian and the 180th meridian. Both northern 45×90 points are located on land, while both southern 45×90 points are in remote open ocean locations.
The meridian 90° east of Greenwich is a line of longitude that extends from the North Pole across the Arctic Ocean, Asia, the Indian Ocean, the Southern Ocean, and Antarctica to the South Pole.
Afro-Eurasia is a landmass comprising the continents of Africa, Asia, and Europe. The terms are compound words of the names of its constituent parts. Afro-Eurasia has also been called the "Old World", in contrast to the "New World" referring to the Americas.
This glossary of geography terms is a list of definitions of terms and concepts used in geography and related fields, including Earth science, oceanography, cartography, and human geography, as well as those describing spatial dimension, topographical features, natural resources, and the collection, analysis, and visualization of geographic data. It is split across two articles:
The borders of the oceans are the limits of Earth's oceanic waters. The definition and number of oceans can vary depending on the adopted criteria. The principal divisions of the five oceans are the Pacific Ocean, Atlantic Ocean, Indian Ocean, Southern (Antarctic) Ocean, and Arctic Ocean. Smaller regions of the oceans are called seas, gulfs, bays, straits, and other terms. Geologically, an ocean is an area of oceanic crust covered by water.
The IERS Reference Meridian (IRM), also called the International Reference Meridian, is the prime meridian maintained by the International Earth Rotation and Reference Systems Service (IERS). It passes about 5.3 arcseconds east of George Biddell Airy's 1851 transit circle which is 102 metres (335 ft) at the latitude of the Royal Observatory, Greenwich. Thus it differs slightly from the historical Greenwich Meridian.
The land hemisphere and water hemisphere are the hemispheres of Earth containing the largest possible total areas of land and ocean, respectively. By definition, the two hemispheres do not overlap.
