ScienceIQ.com

Life In The Extreme

Lowly microbes just may be the toughest living things on Earth. They have learned to survive, and indeed flourish, in the harshest environment imaginable, deep-sea rifts. These rifts are chains of undersea active volcanoes that stretch across the ocean floor. Super-hot roiling lava from deep within the Earth's core, plumes of sulfuric particles, ...

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Microbes
Geology

CALIPSO in 2004

From reports of increasing temperatures, thinning mountain glaciers and rising sea level, scientists know that Earth's climate is changing. But the processes behind these changes are not as clear. Two ... Continue reading

CALIPSOin2004
Astronomy

The Kuiper Belt

The Kuiper (pronounced Ki-Per) Belt is often called our solar system's 'final frontier.' This disk-shaped region of icy debris is about 12 to 15 billion kilometers (2.8 billion to 9.3 billion miles) ... Continue reading

TheKuiperBelt
Astronomy

The Strange Spires of Callisto

When NASA's adventurous Galileo spacecraft skimmed a mere 138 km, (123 miles) above the surface of Jupiter's moon Callisto, onboard cameras captured the sharpest pictures ever of that moon's ... Continue reading

CallistoSpires
Medicine

Why Is Blood Pressure Two Numbers?

Blood pressure might better be called heart pressure, for the heart's pumping action creates it. To measure blood pressure, health workers determine how hard the blood is pushing at two different ... Continue reading

WhyIsBloodPressureTwoNumbers

What Causes The Blue Color That Sometimes Appears In Snow And Ice?

BlueColorSnowIceGenerally, snow and ice present us with a uniformly white face. This is because most all of the visible light striking the snow or ice surface is reflected back without any particular preference for a single color within the visible spectrum. The situation is different for that portion of the light which is not reflected but penetrates or is transmitted into the snow. As this light travels into the snow or ice, the ice grains scatter a large amount of light. If the light is to travel over any distance it must survive many such scattering events, that is it must keep scattering and not be absorbed.

The observer sees the light coming back from the near surface layers (mm to cm) after it has been scattered or bounced off other snow grains only a few times and it still appears white. However, the absorption is preferential. More red light is absorbed compared to blue. Not much more, but enough that over a considerable distance, say a meter or more, photons emerging from the snow layer tend to be made up of more blue light than red light. Typical examples are poking a hole in the snow and looking down into the hole to see blue light or the blue color associated with the depths of crevasses in glaciers. In each case the blue light is the product of a relatively long travel path through the snow or ice. So the spectral selection is related to absorption, and not reflection as is sometimes thought.

In simplest of terms, think of the ice or snow layer as a filter. If it is only a centimeter thick, all the light makes it through, but if it is a meter thick, mostly blue light makes it through.