Monday, January 22, 2007

Weather

Weather is an all-encompassing term used to explain all of the many and varied phenomena that can occur in the atmosphere of a planet. The term is normally taken to mean the activity of these phenomena over short periods of time, typically no more than a few days in length. Average atmospheric conditions over significantly longer periods are known as climate. Usage of the two terms often overlaps and the concepts are obviously very closely connected. Weather phenomena result from temperature differences around the globe, which arise primarily because areas closer to the tropics, around the equator, obtain more energy from the Sun than more northern and southern regions, nearer to the Earth's poles.

A secondary cause of temperature differences on the Earth is that different surface areas have differing reflectivity, and therefore absorb and radiate dissimilar amounts of the solar energy they receive. Surface temperature differences cause vertical wind currents. A hot surface heats the air above it, and the air expands and rises, lowering the air pressure and drawing colder air into its place. Rising and expanding air gives up its heat and so cools, which causes it to shrink and sink, increasing air pressure and displacing the air already below it.




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Thursday, January 11, 2007

Warm-blooded

Warm-blooded animals retain thermal homeostasis; that is, they keep their core body temperature at a nearly constant level despite of the temperature of the surrounding environment. This can engage not only the ability to generate heat, but also the ability to cool down.

Warm-blooded animals manage their body temperature by regulating their metabolic rates. Both the terms "warm-blooded" and "cold-blooded" have fallen out of support with scientists, because of the generality of the terms, and due to an increased understanding in this field. Body temperature types do not drop into simple either/or categories. Each term may be replaced with one or more variants. Body temperature maintenance incorporates a wide range of different techniques that result in a body temperature continuum, with the traditional ideals of warm-blooded and cold-blooded being at opposite ends of the spectrum.




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Thursday, January 04, 2007

Computer graphics

Computer graphics is the field of visual computing, where one utilizes computers both to generate visual images synthetically and to integrate or alter visual and spatial information sampled from the real world. The first major advance in computer graphics was the development of Sketchpad in 1962 by Ivan Sutherland.

This field can be divided into several areas: real-time 3D rendering , computer animation, video capture and video creation rendering, special effects editing , image editing, and modeling . Development in computer graphics was first fueled by academic interests and government sponsorship. However, as real-world applications of computer graphics in broadcast television and movies proved a viable alternative to more traditional special effects and animation techniques, commercial parties have increasingly funded advances in the field. It is often thought that the first feature film to use computer graphics was 2001: A Space Odyssey , which attempted to show how computers would be much more graphical in the future.




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