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  2. Gravitropism - Wikipedia

    en.wikipedia.org/wiki/Gravitropism

    Gravitropism (also known as geotropism) is a coordinated process of differential growth by a plant in response to gravity pulling on it. It also occurs in fungi. Gravity can be either "artificial gravity" or natural gravity. It is a general feature of all higher and many lower plants as well as other organisms.

  3. Troposphere - Wikipedia

    en.wikipedia.org/wiki/Troposphere

    The troposphere is the lowest layer of the atmosphere of Earth. It contains 80% of the total mass of the planetary atmosphere and 99% of the total mass of water vapor and aerosols, and is where most weather phenomena occur. [1] From the planetary surface of the Earth, the average height of the troposphere is 18 km (11 mi; 59,000 ft) in the ...

  4. Tundra of North America - Wikipedia

    en.wikipedia.org/wiki/Tundra_of_North_America

    The adversity of soil and climatic conditions proves to low production levels, as well as little biomass accumulation due to slow rates of nutrient release in cold and wet soils, specifically as a result of limited nitrogen and phosphorus (Nadelhoffer et al. 1996) Additionally, there are low temperatures and strong winds in the tundra causing most vegetation to be dominated by woody plants ...

  5. Hydrostatic equilibrium - Wikipedia

    en.wikipedia.org/wiki/Hydrostatic_equilibrium

    Hydrostatic equilibrium is the distinguishing criterion between dwarf planets and small solar system bodies, and features in astrophysics and planetary geology. Said qualification of equilibrium indicates that the shape of the object is symmetrically rounded, mostly due to rotation, into an ellipsoid, where any irregular surface features are ...

  6. Solar System - Wikipedia

    en.wikipedia.org/wiki/Solar_System

    720,000 km/h (450,000 mi/h) [10] Orbital period. ~230 million years [10] The Solar System[d] is the gravitationally bound system of the Sun and the objects that orbit it. [11] It formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc.

  7. Water distribution on Earth - Wikipedia

    en.wikipedia.org/wiki/Water_distribution_on_Earth

    The total volume of water on Earth is estimated at 1.386 billion km 3 (333 million cubic miles), with 97.5% being salt water and 2.5% being freshwater. Of the freshwater, only 0.3% is in liquid form on the surface. [2][3][4] Because the oceans that cover roughly 70.8% of the area of Earth reflect blue light, Earth appears blue from space, and ...

  8. Altitudinal zonation - Wikipedia

    en.wikipedia.org/wiki/Altitudinal_zonation

    Altitudinal zonation (or elevational zonation[1]) in mountainous regions describes the natural layering of ecosystems that occurs at distinct elevations due to varying environmental conditions. Temperature, humidity, soil composition, and solar radiation are important factors in determining altitudinal zones, which consequently support ...

  9. Geology of Venus - Wikipedia

    en.wikipedia.org/wiki/Geology_of_Venus

    The hemispheric view of Venus, as revealed by more than a decade of radar investigations culminating in the 1990–1994 Magellan mission, is centered at 180 degrees east longitude. The geology of Venus is the scientific study of the surface, crust, and interior of the planet Venus. Within the Solar System, it is the one nearest to Earth and ...