Global Warming

Global warming is the increase in the average temperature of Earth's near-surface air and oceans since the mid-20th century and its projected continuation. According to the 2007 Fourth Assessment Report by the Intergovernmental Panel on Climate Change (IPCC), global surface temperature increased 0.74 ± 0.18 °C (1.33 ± 0.32 °F) during the 20th century.^[2][A] Most of the observed temperature increase since the middle of the 20th century has been caused by increasing concentrations of greenhouse gases, which result from human activity such as the burning of fossil fuel and deforestation.^[3] Global dimming, a result of increasing concentrations of atmospheric aerosols that block sunlight from reaching the surface, has partially countered the effects of warming induced by greenhouse gases.

Climate model projections summarized in the latest IPCC report indicate that the global surface temperature is likely to rise a further 1.1 to 6.4 °C (2.0 to 11.5 °F) during the 21st century.^[2] The uncertainty in this estimate arises from the use of models with differing sensitivity to greenhouse gas concentrations and the use of differing estimates of future greenhouse gas emissions. An increase in global temperature will cause sea levels to rise and will change the amount and pattern of precipitation, probably including expansion of subtropical deserts.^[4] Warming is expected to be strongest in the Arctic and would be associated with continuing retreat of glaciers,permafrost and sea ice. Other likely effects include changes in the frequency and intensity ofextreme weather events, species extinctions, and changes in agricultural yields. Warming and related changes will vary from region to region around the globe, though the nature of these regional variations is uncertain.^[5] As a result of contemporary increases in atmospheric carbon dioxide, the oceans have become more acidic, a result that is predicted to continue.^[6][7]

The scientific consensus is that anthropogenic global warming is occurring.^{[8][9][10][B]}Nevertheless, political and public debate continues. The Kyoto Protocol is aimed at stabilizing greenhouse gas concentration to prevent a "dangerous anthropogenic interference".^[11] As of November 2009, 187 states had signed and ratified the protocol.^[12]

Properties of Ocean Water

Properties of Ocean Water,(:

Temperature		Earth receives its warmth from the sun. Because the world rotates on an angle to its path around the sun, radiation is spread more evenly and seasons are experienced worldwide. Read what underwater photographers need to know about light in the sea and other physical properties.
Chemical properties		Sea water consists of salt and other minerals. They are important for life.  Visit the page with sea water properties, including dissolved gases.(4p)
Physical properties		The ocean's physical properties like temperature, salinity and density are crucial to the ways in which the ocean water moves.
Productivity		The ocean's reservoir in resources seems inexhaustible, but is it? This chapter looks at the ocean's capacity to feed humans and to recycle their wastes.
soil		Also visit our large section about soil, its properties, geology and fertility and how we are losing it, perhaps the world's foremost problem! Read how the sea suffers and degrades, and read about our revolutionary discoveries about sick seas.

go back to the oceanography contents index.

Carbon Cycle

The carbon cycle is the biogeochemical cycle by which carbon is exchanged among thebiosphere, pedosphere, geosphere, hydrosphere, and atmosphere of the Earth. It is one of the most important cycles of the earth and allows for carbon to be recycled and reused throughout the biosphere and all of its organisms.^{[citation needed]}

The carbon cycle was initially discovered by Joseph Priestley and Antoine Lavoisier, and popularized by Humphry Davy.^[1] It is now usually thought of as including the following major reservoirs of carbon interconnected by pathways of exchange:

• The atmosphere
• The terrestrial biosphere, which is usually defined to include fresh water systems and non-living organic material, such as soil carbon.
• The oceans, including dissolved inorganic carbon and living and non-living marine biota,
• The sediments including fossil fuels.
• The Earth's interior, carbon from the Earth's mantle and crust is released to the atmosphere and hydrosphere by volcanoes and geothermal systems.

The annual movements of carbon, the carbon exchanges between reservoirs, occur because of various chemical, physical, geological, and biological processes. The ocean contains the largest active pool of carbon near the surface of the Earth, but the deep ocean part of this pool does not rapidly exchange with the atmosphere in the absence of an external influence, such as a black smoker or an uncontrolled deep-water oil well leak.

The global carbon budget is the balance of the exchanges (incomes and losses) of carbon between the carbon reservoirs or between one specific loop (e.g., atmosphere ↔ biosphere) of the carbon cycle. An examination of the carbon budget of a pool or reservoir can provide information about whether the pool or reservoir is functioning as a source or sink for carbon dioxide.

Video: http://www.5min.com/Video/Learn-about-The-Carbon-Cycle-117566979

Temperature Inversion

A temperature inversion is a thin layer of the atmosphere where the decrease in temperature with height is much less than normal (or in extreme cases, the temperature increases with height). An inversion, also called a "stable" air layer, acts like a lid, keeping normal convective overturning of the atmosphere from penetrating through the inversion. This can cause several weather-related effects. One is the trapping of pollutants below the inversion, allowing them to build up. If the sky is very hazy, or is sunsets are very red, there is likely an inversion somewhere in the lower atmosphere. This happens more frequently in high pressure zones, where the gradual sinking of air in the high pressure dome typically causes an inversion to form at the base of a sinking layer of air. Another effect is making clouds spread out and take on a flattened appearance. Still another effect is to prevent thunderstorms from forming. Even in an air mass that is hot and humid in the lowest layers, thunderstorms will be prevented if an inversion is keeping this air from rising. The opposite of a temperature inversion is anunstable air layer.

Spiral Galaxie

A spiral galaxy is a certain kind of galaxy originally described by Edwin Hubble in his 1936 workThe Realm of the Nebulae^[1] and, as such, forms part of the Hubble sequence. Spiral galaxies consist of a flat, rotating disk containing stars, gas and dust, and a central concentration of stars known as the bulge. These are surrounded by a much fainter halo of stars, many of which reside inglobular clusters.


Video: http://videos.howstuffworks.com/nasa/13490-ask-an-astronomer-spiral-galaxies-video.htm