Land area

Rough geological breakdown of the earth's crust : gray-blue tones indicate oceanic crust , all other colors indicate continental crust, which, however, also underlies marine areas to a small extent.

In the geosciences (especially geography ) , land area, land mass or mainland is largely defined as that part of the earth's surface that rises above sea level and is therefore not covered by the water of the oceans and seas even at high tide . Some land areas known as the Depression are below sea level. The fact that these land areas are not inundated by sea water is possible because they are shielded from sea water either by natural ridges or by building dykes. Fresh water reaching these areas is often pumped out to higher areas.

The earth's land area is around 149.4 million km² - 29.3% of the earth's surface - and is mainly attributable to the continents: Eurasia (geographical- geological umbrella term for Europe and Asia), Africa, America (North America, Central America and South America), Antarctica and Australia.

In particular, the large contiguous land masses of the earth - the continents (in the classic geographical sense) - are referred to as mainland. However, these are somewhat smaller than the contiguous masses of the continental crust (continents in the geological sense), which also include the shallow marginal seas - the shelf areas . The border regions between the mainland and the sea are called coasts (outdated: shores ), whereby land areas can also be added to a coastal region that are not directly on the coastline (see, for example, the terms east coast and west coast of the USA ). In contrast to this is the inland , a land area that is relatively far from the sea on all sides.

Smaller and scattered areas of land within bodies of water are called islands and are not counted as mainland or land mass in the preceding sense (see the term continental Europe ). In the case of larger and smaller ones, the main island is also referred to as the mainland (English also often mainland ) and the offshore islands off the main island are called secondary islands .

In contrast to water surfaces, land areas react very quickly and strongly to varying solar radiation because they have a lower specific heat than water. This is why the land cools down faster than the sea overnight and warms up faster during the day. These temperature differences, which are often considerable during the day, are the cause of many regional wind systems . The same applies to the annual temperature change over the course of the seasons. The larger the land mass, the more clearly this effect becomes apparent and is typical of a continental climate .

Land area

See also