Discount Fabric Online

Why is the sky blue?
The sky is blue partly because air scatters short-wavelength light in preference to longer wavelengths. Combined, these effects scatter (bend away in all directions) some short, blue light waves while allowing almost all longer, red light waves to pass straight through. When we look toward a part of the sky not near the sun, the blue color we see is blue light waves scattered down toward us from the white sunlight passing through the air overhead. Near sunrise and sunset, most of the light we see comes in nearly tangent to the Earth's surface, so that the light's path through the atmosphere is so long that much of the blue and even yellow light is scattered out, leaving the sun rays and the clouds it illuminates red.

Scattering and absorption are major causes of the attenuation of radiation by the atmosphere. Scattering varies as a function of the ratio of the particle diameter to the wavelength of the radiation. When this ratio is less than about one-tenth, Rayleigh scattering occurs in which the scattering coefficient varies inversely as the fourth power of the wavelength. At larger values of the ratio of particle diameter to wavelength, the scattering varies in a complex fashion described, for spherical particles, by the Mie theory; at a ratio of the order of 10, the laws of geometric optics begin to apply.

Why is the sky blue instead of violet?
Because of the strong wavelength dependence (inverse fourth power) of light scattering according to Raleigh's Law, one would expect that the sky would appear more violet than blue, the former having a shorter wavelength than the latter. There is a simple physiological explanation for this apparent conundrum. Simply put, the human eye cannot detect violet light in presence of light with longer wavelengths. There is a reason for this. It turns out that the human eye's high resolution color-detection system is made of proteins and chromophores (which together make up photoreceptor cells or "Cone" structures in the eye's fovea) that are sensitive to different wavelengths in the visible spectrum (400 nm–700 nm). In fact, there are three major protein-chromophore sensors that have peak sensitivities to yellowish-green (564 nm), bluish-green (534 nm), and blue-violet (420 nm) light. The brain uses the different responses of these chromophores to interpret the spectrum of the light that reaches the retina.

When one experimentally plots the sensitivity curves for the three color sensors (identified here as long (L), middle (M), and short (S) wavelength), three roughly "bell-curve" distributions are seen to overlap one another and cover the visible spectrum. We depend on this overlap for color sensing to detect the entire spectrum of visible light. For example, monochromatic violet light at 400 nm mostly stimulates the S receptors, but also slightly stimulates the L and M receptors, with the L receptor having the stronger response. This combination of stimuli is interpreted by the brain as violet. Monochromatic blue light, on the other hand, stimulates the M receptor more than the L receptor. Skylight is not monochromatic; it contains a mixture of light covering much of the spectrum. The combination of strong violet light with weaker blue and even weaker green and yellow strongly stimulates the S receptor, and stimulates the M receptor more than the L receptor. As a result, this mixture of wavelengths is perceived by the brain as blue rather than violet.

and

Why is the sea blue?
A common misconception concerning the color of water in large bodies, such as the ocean, is that the blue is due to the reflections from the sky on its surface. This is not true, but was believed to be so decades ago. The real reason the ocean is blue is because the water, pure water, is blue. Yes, according to its frequency spectra, water is a very light shade of turquoise blue. But you need a huge amount of it to really see its color. It’s like a teaspoon of oil, it looks transparent on a white spoon, but in the bottle looks yellowish.

If the ocean owed its color to the sky, it would be a lighter shade of blue and it would be white on cloudy days. You can see clouds reflected in the surface on the sea, but they don’t completely change its color. Some constituents of sea water can influence the shade of blue you see in the ocean. This is why it can look greener or bluer in different areas. Swimming pools with white bottom, would have water that look transparent not turquoise blue, as it is observed even in indoor pools, where there’s no sky to be reflected. The scientific explanation involves the theory of radiative transfer (absorption and scattering), and material electromagnetic spectra.

Particular matter
The color of a water sample is caused by both dissolved and particulate material in water, and is measured in Hazen Units (HU). Either of these components can be deeply colored, for instance dissolved organic molecules called tannins can result in dark brown colors, or algae floating in the water ("particles") can impart a green color. But in a lot of cases water is a clear to neutral color due to a lack of pigments in the water. (e.g. the sea)

The color of a water sample can be reported as:

1. Apparent color
2. True color

Apparent color is the color of the whole water sample, and consists of color due to both dissolved and suspended components.

True color is measured by filtering the water sample to remove all suspended material, and measuring the color of the filtered water, which represents color due to dissolved components.

Testing for color can be a quick and easy test which often reflects the amount of organic material in the water (although certain inorganic components like iron or manganese can also impart color).

You could get more information from the 2 links below...

1 yd 35 South Sea Imports Fabric Born In The USA Blue $16.90 Time Remaining: 8h 28m Buy It Now for only: $16.90

LONE WOLVES SOUTH SEA IMPORTS PICTURES of WOLF PACK $7.99 Time Remaining: 10h 42m Buy It Now for only: $7.99

Hoffman Hand Painted Bali Batik Royal Sea Shells Fabric $10.50 Time Remaining: 12h 19m Buy It Now for only: $10.50

I Lighthouses By The Sea on Lt Blue White Fabric $5.99 Time Remaining: 12h 41m Buy It Now for only: $5.99

Lighthouse East Coast Harbor Sailboats Ocean Sea Tapestry Fabric Panel 5 x 7 $3.99 (1 Bid) Time Remaining: 13h 48m

Lighthouse East Coast Harbor Sailboats Ocean Sea Tapestry Fabric Panel 5 x 7 $3.99 Time Remaining: 15h 21m

SOUTH SEA LT BLUE DOTS ON WHITE BTY $6.50 Time Remaining: 17h 51m Buy It Now for only: $6.50

KONA BAY Three Seasons Summer 3SEA 09 quilting fabric $6.30 Time Remaining: 21h 5m Buy It Now for only: $6.30

SEA BLUE STRETCH MESH W HOLOGRAPHIC SEQUINS FABRIC 50 WIDE BY THE YARD $29.99 Time Remaining: 1d 24m Buy It Now for only: $29.99

Vestment Silk Brocade fabric Sea blue x Green Butter $21.00 Time Remaining: 1d 3h 56m Buy It Now for only: $21.00

Annette Tatum AT33 Fall House Bloom Sea Fabric By Yd $6.50 Time Remaining: 1d 10h 5m Buy It Now for only: $6.50

Annette Tatum AT35 Fall House Euro Stripe Soft Sea By d $6.50 Time Remaining: 1d 10h 8m Buy It Now for only: $6.50

Annette Tatum AT37 Fall House Mini Flower Sea By Yd $6.50 Time Remaining: 1d 10h 9m Buy It Now for only: $6.50

South Seas Imports Cotton Fabric Soft Blue White Clouds Skies Fat Quarters $3.50 Time Remaining: 1d 12h 29m Buy It Now for only: $3.50

REEF OCEAN SEA TURTLES BRIGHT BLUE GRN Cotton Fabric BTY for Quilting Craft Etc $10.25 Time Remaining: 1d 15h 35m Buy It Now for only: $10.25

By the Sea Shells Blue on White Fabric 2yds Marcus Brothers $11.50 Time Remaining: 1d 15h 49m Buy It Now for only: $11.50

Blue Sea Sailboats Voyage Harbor Ocean Ship 100 Cotton Fabric 55wd BTY $7.95 Time Remaining: 1d 16h 38m

Frog Fabric Novelty South Sea Froggy Ribbit Clouds Yard $6.89 Time Remaining: 1d 16h 43m Buy It Now for only: $6.89

Snuggle Flannel Pajama Quilt Blue Scribble Sea Creatures Octopus Mermaid Fish $5.99 Time Remaining: 1d 21h 44m Buy It Now for only: $5.99

Polyester Georgette jacquard fabric Sea Blue colour $7.00 Time Remaining: 2d 7h 8m Buy It Now for only: $7.00

New Sea Blue Pucker Jacquard Poly Stretch Fabric $3.50 Time Remaining: 2d 10h 59m Buy It Now for only: $3.50

100 Cotton Tree Tops Blue South Sea Imports $7.99 Time Remaining: 2d 14h 10m Buy It Now for only: $7.99

Sea Shells Starfish on Blue Quilting Fabric by Yard 486 $5.79 Time Remaining: 2d 14h 43m Buy It Now for only: $5.79

Debbie Mumm Christmas Fabric Labels South Seas Imports $6.95 Time Remaining: 2d 15h 6m Buy It Now for only: $6.95

Under the Sea Seahorses Tropical Fish Quilting Fabric Panel 44 x 23 CUTE $4.95 Time Remaining: 2d 16h 5m

Duralee Sea Solid Fabric Remnant $9.00 Time Remaining: 2d 21h 12m Buy It Now for only: $9.00

Dolphin Stripe Mermaid Wishes Dan Morris RJR Fish Ocean Sea Blue Purple Pink $4.85 Time Remaining: 3d 10h 49m Buy It Now for only: $4.85

Seahorses Mermaid Wishes Dan Morris RJR Fish Ocean Sea Blue Purple Pink Orange $4.85 Time Remaining: 3d 10h 51m Buy It Now for only: $4.85

Whale Fabric Ocean Sea Life Blue Green Fish Orca Killer $10.00 Time Remaining: 3d 11h 5m Buy It Now for only: $10.00

Hoffman Bali BATIK H 2262 Sea Grass FLORAL Green Blue 1 yard $8.95 Time Remaining: 3d 11h 25m Buy It Now for only: $8.95

Fabri Quilt Cotton Fabric Aqua Blue Antartic Seas FQ $3.50 Time Remaining: 3d 11h 51m Buy It Now for only: $3.50

South Sea Imports fabric TALL SHIPS Blue Anchors $9.50 Time Remaining: 3d 11h 55m Buy It Now for only: $9.50

South Sea Imports Fabric 155 414 Blue Stripe 2pcs $20.99 Time Remaining: 3d 14h 8m Buy It Now for only: $20.99

New Sea Turtle Fabric BTY Fish Ocean $4.95 Time Remaining: 3d 14h 33m Buy It Now for only: $4.95

Timeless Treasures Sea Turtles Quilt Fabric 6392 Blue $9.89 Time Remaining: 3d 15h 30m Buy It Now for only: $9.89

Baby Dumb Dot Sea Michael Miller 1 yard $9.75 Time Remaining: 3d 17h 47m Buy It Now for only: $9.75

Blue sea waves white foam brown rocks Mendocino PB Textiles BTY $9.99 Time Remaining: 3d 18h 23m Buy It Now for only: $10.99

Sandy Shores Sea Shells Beach Blue Windham Fabric Yard $10.50 Time Remaining: 3d 18h 51m Buy It Now for only: $10.50

Blue Fabric with White Sea Shells $0.99 Time Remaining: 3d 19h

NAUTICAL WHALE SEA CUTE FABRIC MATERIAL 19 x 22 NEW $3.00 Time Remaining: 3d 19h 51m Buy It Now for only: $5.00

New Lighthouse Fabric BTY Nautical Ocean Sea $4.95 Time Remaining: 3d 19h 54m Buy It Now for only: $4.95

Cute and Colorful Animated Sea Life Fish Fabric on BLUE $4.25 Time Remaining: 3d 21h 15m Buy It Now for only: $4.25

Sea Snail Stripe Novelty Fabric on BlueCUTE $4.25 Time Remaining: 3d 21h 15m Buy It Now for only: $4.25

South Sea Imports Vegetables on Blue Fabric BTY 3662 $6.99 Time Remaining: 4d 9h 54m Buy It Now for only: $6.99

HALF YARD Blue Butterfly Heart Dots MARIA TRAD South Sea Imports Fabric 1 2 YARD $3.99 Time Remaining: 4d 12h 2m Buy It Now for only: $3.99

Majestic 1 2 YD Batik 4303 16 Sea Blue $4.18 Time Remaining: 4d 18h 22m Buy It Now for only: $4.18

Moda Marbles yd Stormy Sea 9881 66 $5.50 Time Remaining: 4d 19h 26m Buy It Now for only: $5.50

Timeless Batik Fabric JADE Blue Green Seaweed Sea Anemone Quilting $10.50 Time Remaining: 4d 20h 50m Buy It Now for only: $10.50

FAT QUARTER Turtle Honu AQUA Blue Surfs Up Sea Fabric $4.00 Time Remaining: 4d 21h 30m Buy It Now for only: $4.00

FAT QUARTER Gray Whales on Blue Ocean Sea Fabric $5.00 Time Remaining: 4d 21h 35m Buy It Now for only: $5.00

BOOAK Fabric KNIT Cotton Bright SEA WORLD Life Dolphin FISH Turtle Blue Whale FQ $6.65 Time Remaining: 4d 21h 48m Buy It Now for only: $6.65

CHILDREN OF THE SEA FULL MOON OVER IN STAR FILLED SKY $8.99 Time Remaining: 4d 22h 2m Buy It Now for only: $8.99

3 FINISHED FABRIC PANELS IN SEA BLUE COLORS $4.99 Time Remaining: 4d 22h 14m Buy It Now for only: $4.99

1 Panel of Baby Bibs Duck sea horse Quilted Fabric $3.99 Time Remaining: 5d 9h 40m Buy It Now for only: $3.99

1 2 yard Michael Miller Sea Gulls Sky Blue Background $3.50 Time Remaining: 5d 10h 45m Buy It Now for only: $3.50

Fairy Frost SPA Light Sea Green Michael Miller TOT Cotton Fabric FQ or Yardage $2.75 Time Remaining: 5d 12h 45m Buy It Now for only: $2.75

TROPICAL OCEAN ANIMAL REEF STINGRAY SWIMMING in SEA $9.99 Time Remaining: 5d 13h 28m Buy It Now for only: $9.99

TROPICAL OCEAN SEALIFE REEF SEA TURTLES SWIMMING $9.99 Time Remaining: 5d 13h 33m Buy It Now for only: $9.99

P Kaufmann Fabric By the Sea Periwinkle $13.98 Time Remaining: 5d 14h 21m Buy It Now for only: $13.98

MICHAEL MILLER TA DOT Sea fabric by yard $9.25 Time Remaining: 5d 16h 46m Buy It Now for only: $9.25

Hoffman Hand Painted Bali Batik Royal Sea Shells Fabric $9.50 Time Remaining: 5d 17h 21m Buy It Now for only: $10.50

Alphabet Soup DOTS Stripe green blue brown SOUTH SEAS sold By the yard $6.95 Time Remaining: 5d 17h 57m Buy It Now for only: $6.95