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Category Archives: Phenomena
What was the ring around the sun last week?
Last week there was a ring around the sun for much of the day. This ring is called a halo and is caused by ice crystals interacting with sunlight.
A halo is a whitish ring that encircles but does not touch the sun. It can also have some color; the most discernible is a faint red tint around the inside of the halo. It is an optical phenomenon that owes its existence to the bending of light by ice crystals, much like the “rainbow crystals” you may hang in your sunlit windows. Continue reading
What is a ‘bomb cyclone’?
The term “bomb cyclone” refers to the formation and rapid development of a mid-latitude cyclone. A mid-latitude cyclone is a large-scale, low-pressure system, characteristic of the middle latitudes, that has counter-clockwise flow around its center (in the Northern Hemisphere).
A primary measure of development in these storms is a drop in the atmospheric pressure at the center of the storm. Air near the ground is forced to move inward to the center of the circulation — this is known as convergence. Continue reading
Did climate change kill the dinosaurs?
Sixty-six million years ago, the age of the dinosaurs ended abruptly, coinciding with the extinction of about 75 percent of the total number of living species.
Evidence and climate modeling indicate that global wildfires resulted from a collision with a massive asteroid that could have lofted large amounts of soot into the atmosphere. The smoke would have plunged Earth into darkness for nearly two years, which would have shut down photosynthesis, drastically cooled the planet, and contributed to the mass extinctions as evidenced in the fossil record. Continue reading
What’s happening with the ozone hole?
Encouraging news arrived this week regarding the size of the Southern Hemisphere ozone hole. NASA reported that this year’s ozone hole (which peaked on Sept. 11 at 7.6 million square kilometers) was the smallest since 1988, just years after the problem was first identified.
Though a number of factors contribute to the annual size of the ozone hole, it is beyond doubt that the leading factor is the reduction of chlorofluorocarbons (CFCs), industrial chemicals long used for refrigeration among other things. Continue reading
Why is lightning white?
Lightning is a huge electrical discharge.
Static charges form in a storm composed of ice crystals and liquid water drops. Turbulent winds inside the storm cause particles to rub against one another, causing electrons to be stripped off, making the particles either negatively or positively charged. Continue reading
