Saturday, January 25, 2014

Plate Collision

Deformation, deflection, and detachment are observable when land masses collide. Via the immense pressure of colliding tectonic plates, horizontally deposited sedimentary rock, distinguished by distinctively colored, vertically-stratified slabs, can be:
  1. Squeezed into wavy layers forming synclines and anticlines (right); or
  2. Broken up so that the deeper layers (older) of rock pile on top of shallower (newer) layers. A phenomena called a thrust fault; or
  3. Forced to strike or slip along a plane creating a horizontally detached strike-slip fault.

Piqiang Fault, a strike-slip fault

Piqiang Fault is a dramatic example of a strike-slip fault in the Gobi desert. The sedimentary rock layers are offset by about 2 miles. Pressure from colliding tectonic plates, i.e., the northward moving Indian plate and the Eurasian plate, caused Piqiang Fault.

Civilization exists by geological consent, subject to change without notice.
Will Durant


Saturday, January 18, 2014

Atmospheric Oxygen

Blue-green algae bloom
Photosynthesis on land (~ 55%) and photosynthesis in the ocean (~ 45%) account for nearly 100% of Earth's atmospheric oxygen.

A fraction comes from the breakup of water (photolysis) from ultraviolet radiation.
"The oxygen in today's atmosphere is almost entirely the result of photosynthetic living, which had its start with the appearance of blue-green algae among the microorganisms."
Lewis Thomas
The annual gain of atmospheric oxygen is shown below:
Photosynthesis (land)
Photosynthesis (ocean)
Photolysis of N2O
Photolysis of H2O
Total ~ 30,000
units 1010 kg O2 per year
Plants, algae, and cyanobacteria perform photosynthesis which maintains atmospheric oxygen and supplies all of the organic compounds and most of the energy necessary to sustain life in Earth's biosphere.
"One hundred and fifty years ago, the monster began, this country had become a place of industry. Factories grew on the landscape like weeds. Trees fell, fields were up-ended, rivers blackened. The sky choked on smoke and ash, and the people did, too, spending their days coughing and itching, their eyes turned forever toward the ground. Villages grew into town, towns into cities. And people began to live on the earth rather than within it."
Patrick Ness, A Monster Calls

An LED screen in Tiananmen Square showing the rising sun
in a tourism advertisement for China’s Shandong province
while Beijing is shrouded in smog. 16 January 2014.


Saturday, January 11, 2014

The Polar Vortex

Polar Vortex over Maine, 1985
The polar vortex is circulation of upper-level, stratospheric winds that normally surround the North Pole. The circulating winds flow around a low-pressure system in a counterclockwise direction.

Occasionally this vortex becomes distorted so that it dips much farther south allowing lobes of arctic air to blanket parts of North America, northern Europe and Asia.

When the polar vortex is perturbed, temperatures tend to be colder in the mid-latitudes across the US, Europe, and Eurasia.
Perturbed Polar Vortex

The vortex typically lies directly over the North Pole and confines the cold air to the Arctic. Warm air masses pushing north will occasionally shift the polar vortex off the North Pole.

Normally circular, the vortex can become distorted and elongated, as shown in the animation, allowing arctic air to spill into the mid-latitudes.
"Men argue. Nature acts."
Scientists have discovered a statistically significant link between Siberian snow cover and the behavior of the winter polar vortex.

AER scientists (Atmospheric and Environmental Research) use Siberian snow cover measured from the previous October to project the strength of the winter polar vortex. Using those projections, AER forecasts winter temperatures for much of North America and Northern Europe and Northern Eurasia.
“Three feet of ice does not result from one day of cold weather.”
― Chinese Proverb
The polar vortex of January 2014 could be a side effect of climate change. Climate scientists recognize that distortions of the jet stream cause extreme cold snaps in winter and anomalous heat waves in summer.


Saturday, January 4, 2014

Earth as Perceptible Dot

In an image made 900 million miles away from us, the Earth and the Moon appear as two barely perceptible dots.

The rings of Saturn with the Earth and Earth's moon in the distant background
Photo by NASA/JPL-Caltech/Space Science Institute
"It is hard to believe while standing among 7 billion other people on this huge and diverse planet we call home that it is not the center of the universe in the same way that it is the center of our lives."
― Madeleine Fowler, Never before have we felt so small
The image of Saturn's rings with the Earth and Earth's moon in the distant background taken from the Cassini Spacecraft on the Solstice Mission makes our earthly habitat a tiny fish in an infinite pond.

Carl Sagan offers us perspective on what he called "that pale blue dot":
"The earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that in glory and in triumph they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of the dot on scarcely distinguishable inhabitants of some other corner of the dot. How frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Our posturings, our imagined self-importance, the delusion that we have some privileged position in the universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity -- in all this vastness -- there is no hint that help will come from elsewhere to save us from ourselves. It is up to us. It's been said that astronomy is a humbling, and I might add, a character-building experience. To my mind, there is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly and compassionately with one another and to preserve and cherish that pale blue dot, the only home we've ever known."