Since their discovery 120 years ago, strangely luminescent clouds called noctilucent clouds have been creeping slowly toward the equator.
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| ©Denver Post
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| This hauntingly beautiful noctilucent cloud was photographed over the Juneau, Alaska, ice field in 1998. Once confined to Earth's poles, the clouds have been spotted above Colorado.
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A NASA satellite has captured the first occurrence this summer of mysterious iridescent polar clouds that form 50 miles above Earth's surface.
The first observations of these clouds by the Aeronomy of Ice in the Mesosphere (AIM) satellite occurred above 70 degrees north on May 25. Observers on the ground began seeing the clouds on June 6 over northern Europe. AIM is the first satellite mission dedicated to the study of these unusual clouds.
These mystifying clouds are called Polar Mesospheric Clouds, or PMCs, when they are viewed from space and referred to as "night-shining" clouds, or noctilucent clouds, when viewed by observers on Earth. The clouds form during the Northern Hemisphere's summer season that begins in mid-May and extends through the end of August. They are being seen by AIM's instruments more frequently as the season progresses. The clouds also are seen in the high latitudes of the Southern Hemisphere during the summer months.
Very little is known about how these clouds form over the poles, why they are being seen more frequently and at lower latitudes than ever before, or why they have been growing brighter. AIM will observe two complete polar mesospheric cloud seasons over both poles, documenting for the first time the entire, complex life cycle of PMCs.
Comment: The article starts out by assuming it's a change in the atmosphere that's creating the clouds, but then later on says, "The Cosmic Dust Experiment is recording the amount of space dust that enters Earth's atmosphere to help scientists assess the role this dust plays in PMC formation." So which is it? Could the dust be a pre-swarm indicator?
If so, the dust would have to come from particles big enough not to be blasted out by the solar wind, implying that small meteors are responsible which would explain the increasing number of fireballs seen worldwide in the past few years. It's all speculation, but the point is not to assume that it's an atmospheric change only.
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| ©AP Photo/Petros Giannakouris
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| Children play in an Athens park in front of smoke from a forest fire in Dervenohoria, north-west of the capital
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ATHENS, Greece - Wildfires swept through Greece on Thursday, killing two people and destroying homes after days of record temperatures of more than 100 degrees that led to at least nine heatstroke deaths and extensive power cuts.
Flood-battered Britain is on alert for further chaos and loss of life this weekend as fears grow that more heavy downpours are on the way.
Forecasters say an "organised band of persistent showers" is set to sweep the country on Friday and Saturday, bringing several more inches of rain to many already-saturated regions.
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| DELUGE: An aerial view of flooded homes in Catcliffe near Sheffield.
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AFPWed, 27 Jun 2007 16:46 UTC
Two elderly people died as a withering heatwave blasted Cyprus for a fourth day Wednesday and electricity workers went on strike cutting air conditioning, doctors and officials said.
The overall toll from the baking temperatures climbed to three with the deaths or a man and a woman in their mid-90s, as the thermometer soared to 42 degrees Celsius (108 Fahrenheit).
AFPThu, 28 Jun 2007 16:06 UTC
A strong earthquake packing a magnitude of 6.7 has hit Papua New Guinea (PNG), but there are no immediate reports of damage or a tsunami.
The US Geological Survey says the undersea quake struck 219 kilometres (136 miles) south-west of the town of Arawa, in the politically troubled region of Bougainville.
Carl Zimmer
DiscoverThu, 28 Jun 2007 09:15 UTC
Every living thing on Earth shares a long, colorful history. Our planet was born into a maelstrom 4.5 billion years ago, and for the next 600 million years a steady bombardment of primordial debris made the surface uninhabitable. The blitz finally tapered off 3.8 billion years ago. Then within about 50 million years later - practically an instant in geologic time - life irrevocably established itself. Since then, it has evolved into everything from bacteria to toadstools to mudskippers to humans. Outwardly these species vary wildly, but at the molecular level they are staggeringly uniform. They all use DNA to encode genetic information. They all use RNA molecules as messengers to transfer the information from DNA to cellular factories called ribosomes, which then build proteins, which in turn drive our metabolisms and form the structures of our cells. In short, every species seems descended from a common ancestor whose attributes define what scientists mean when they say "life as we know it."
APWed, 27 Jun 2007 23:11 UTC
Power blackouts hit more than a dozen parts of Athens on Wednesday and 95 fires were reported around Greece as a deadly heat wave plaguing southeast Europe simmered on.
Temperatures of up to 46 C have killed at least 42 people in Italy and Balkan countries in the last week, including 23 deaths in Romania. Two deaths were reported, in Bulgaria and Cyprus, on Wednesday.
Tens of thousands of Britons were left without power in northern England on Monday after an electricity substation flooded so badly engineers were only able to get back into it on Tuesday, network operator National Grid said.
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| ©REUTERS/Owen Humphreys
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| Aerial view of the flooded village of Catcliffe near Sheffield, following two days of heavy rain which caused floods in Yorkshire, June 26, 2007.
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About 35,000 homes and businesses had their electricity cut on Monday after the Neepsend substation in Sheffield flooded in torrential rain.
CBCTue, 26 Jun 2007 16:32 UTC
Heat contained in the Earth's crust acts like a life-jacket, and without it much of North America would be under water, suggests research at the University of Utah.
The flooding predicted because of global warming is a much more immediate threat, the researchers note. It would take billions of years for North American rock to cool to the point where it will become denser and sink enough to put much of the continent under water.
The research suggests for the first time that about half the elevation of any place in North America is related to temperature differences within the Earth's crust, with most of the rest due to differences in what the rocks are made of.
Comment: The article starts out by assuming it's a change in the atmosphere that's creating the clouds, but then later on says, "The Cosmic Dust Experiment is recording the amount of space dust that enters Earth's atmosphere to help scientists assess the role this dust plays in PMC formation." So which is it? Could the dust be a pre-swarm indicator?
If so, the dust would have to come from particles big enough not to be blasted out by the solar wind, implying that small meteors are responsible which would explain the increasing number of fireballs seen worldwide in the past few years. It's all speculation, but the point is not to assume that it's an atmospheric change only.