The sun's energy is the primary source of energy for all surface phenomena and life on Earth. Combined with the material of the Earth (including the molecules held close by the Earth's gravitational force called the atmosphere), this energy provides for the immense diversity of life forms that are found on the Earth. We will now look in detail at solar energy and its interplay with the constituents of the Earth's atmosphere.
credit:http://telstar.ote.cmu.edu/environ/m3/s2/02sun.shtml
Thursday, 19 July 2012
The Sun’s Energy is in Many Things
The energy from the sun makes rain fall and wind blow. We can capture that energy with dams
and windmills.
Coal, oil, and natural gas were made from prehistoric plants and animals. The energy in them
came from the sun. We use that energy to cook our food, warm our houses, run our cars, and
make electricity
and windmills.
Coal, oil, and natural gas were made from prehistoric plants and animals. The energy in them
came from the sun. We use that energy to cook our food, warm our houses, run our cars, and
make electricity
Monday, 16 July 2012
Sunlight
Sunlight is Earth's primary source of energy. The solar constant is the amount of power that the Sun deposits per unit area that is directly exposed to sunlight. The solar constant is equal to approximately 1,368 W/m2 (watts per square meter) at a distance of one astronomical unit (AU) from the Sun (that is, on or near Earth). Sunlight on the surface of Earth is attenuated by the Earth's atmosphere so that less power arrives at the surface—closer to 1,000 W/m2 in clear conditions when the Sun is near the zenith.
credit:http://en.wikipedia.org/wiki/Sun
Name and etymology
The English proper noun Sun developed from Old English sunne (around 725, attested in Beowulf), and may be related to south. Cognates to English sun appear in other Germanic languages, including Old Frisian sunne, sonne ("sun"), Old Saxon sunna, Middle Dutch sonne, modern Dutch zon, Old High German sunna, modern German Sonne, Old Norse sunna, and Gothic sunnō. All Germanic terms for the Sun stem from Proto-Germanic *sunnōn.
In relation, the Sun is personified as a goddess in Germanic paganism; Sól/Sunna.Scholars theorize that the Sun, as Germanic goddess, may represent an extension of an earlier Proto-Indo-European sun deity due to Indo-European linguistic connections between Old Norse Sól, Sanskrit Surya, Gaulish Sulis, Lithuanian Saulė, and Slavic Solnitse.
The English weekday name Sunday is attested in Old English (Sunnandæg; "Sun's day", from before 700) and is ultimately a result of a Germanic interpretation of Latin dies solis, itself a translation of the Greek heméra helíou. The Latin name for the star, Sol, is widely known but is not common in general English language use; the adjectival form is the related word solar. The term sol is also used by planetary astronomers to refer to the duration of a solar day on another planet, such as Mars.A mean Earth solar day is approximately 24 hours, while a mean Martian 'sol' is 24 hours, 39 minutes, and 35.244 seconds.
credit:http://en.wikipedia.org/wiki/Sun
In relation, the Sun is personified as a goddess in Germanic paganism; Sól/Sunna.Scholars theorize that the Sun, as Germanic goddess, may represent an extension of an earlier Proto-Indo-European sun deity due to Indo-European linguistic connections between Old Norse Sól, Sanskrit Surya, Gaulish Sulis, Lithuanian Saulė, and Slavic Solnitse.
The English weekday name Sunday is attested in Old English (Sunnandæg; "Sun's day", from before 700) and is ultimately a result of a Germanic interpretation of Latin dies solis, itself a translation of the Greek heméra helíou. The Latin name for the star, Sol, is widely known but is not common in general English language use; the adjectival form is the related word solar. The term sol is also used by planetary astronomers to refer to the duration of a solar day on another planet, such as Mars.A mean Earth solar day is approximately 24 hours, while a mean Martian 'sol' is 24 hours, 39 minutes, and 35.244 seconds.
credit:http://en.wikipedia.org/wiki/Sun
sun
The Sun is the brightest and most familiar object in the sky. Life on Earth would not be possible without it:
The food we eat exists because of sunlight falling on green plants, and the fuel we burn comes either from such plants, or was accumulated by them (in the forms of coal, oil and natural gas) long ago.
The Earth would probably not be fit for life. Life as we know it needs liquid water, and Earth is the only planet to have it: without the Sun, Earth would be an icy rock in space. Even now, Earth is probably the only place in our solar system fit for life: any water on Venus and Mercury would become steam, any on Mars or on more distant planets would freeze.
Sunlight is created
The Sun has no sharply defined surface like that of the Earth, because it is too hot to be anything but gas. Rather, what appears to us as the surface is a layer in the Sun's atmosphere, the "photosphere" (sphere of light) which emits light ("radiates") because ot its high temperature.
All hot substances radiate light, either the visible kind or beyond the rainbow spectrum, in the "infra red" (IR; "below red") and "ultra violet" (UV; "above violet") ranges. This glow [called "black body radiation" by physicists--the glow of a body with no color of its own] is the way a red-hot piece of iron or the filament in an electric light bulb produce light. The hotter the object, the brighter it shines, and the further away from red is its color. Conversely, the color of a hot object (if it is dense) tells us how hot it is. In the case of the Sun, the color of the photosphere suggests a temperature of 5780 degrees Kelvin (degrees Celsius measured from the absolute zero, about 5500° C.)
credit:http://www-spof.gsfc.nasa.gov/stargaze/Sun1lite.htm
All hot substances radiate light, either the visible kind or beyond the rainbow spectrum, in the "infra red" (IR; "below red") and "ultra violet" (UV; "above violet") ranges. This glow [called "black body radiation" by physicists--the glow of a body with no color of its own] is the way a red-hot piece of iron or the filament in an electric light bulb produce light. The hotter the object, the brighter it shines, and the further away from red is its color. Conversely, the color of a hot object (if it is dense) tells us how hot it is. In the case of the Sun, the color of the photosphere suggests a temperature of 5780 degrees Kelvin (degrees Celsius measured from the absolute zero, about 5500° C.)
credit:http://www-spof.gsfc.nasa.gov/stargaze/Sun1lite.htm
Effect on human health
The body produces vitamin D from sunlight (specifically from the UVB band of ultraviolet light), and excessive seclusion from the sun can lead to deficiency unless adequate amounts are obtained through diet.
Sunburn can have mild to severe inflammation effects on skin; this can be avoided by using a proper sunscreen cream or lotion or by gradually building up melanocytes with increasing exposure. Another detrimental effect of UV exposure is accelerated skin aging (also called skin photodamage), which produces a difficult to treat cosmetic effect. Some people are concerned that ozone depletion is increasing the incidence of such health hazards. A 10% decrease in ozone could cause a 25% increase in skin cancer.[19]
A lack of sunlight, on the other hand, is considered one of the primary causes of seasonal affective disorder (SAD), a serious form of the "winter blues". SAD occurrence is more prevalent in locations further from the tropics, and most of the treatments (other than prescription drugs) involve light therapy, replicating sunlight via lamps tuned to specific wavelengths of visible light, or full-spectrum bulbs.A recent study indicates that more exposure to sunshine early in a person’s life relates to less risk from multiple sclerosis (MS) later in life
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