Just as sunflowers turn their heads to catch every sunbeam, so too have we discovered a simple way to get more from our sun.

                                        

Daylight Saving Time gives us the opportunity to enjoy sunny summer evenings by moving our clocks an hour forward in the spring.

Yet, the implementation of Daylight Saving Time has been fraught with controversy since Benjamin Franklin conceived of the idea. Even today, regions and countries routinely change their approaches to Daylight Saving Time.

When we change our clocks

Most of the United States begins Daylight Saving Time at 2:00 a.m. on the second Sunday in March and reverts to standard time on the first Sunday in November. In the U.S., each time zone switches at a different time.

In the European Union, Summer Time begins and ends at 1:00 a.m. Universal Time (Greenwich Mean Time). It begins the last Sunday in March and ends the last Sunday in October. In the EU, all time zones change at the same moment.

                                                                     

          

Spelling and grammar

The official spelling is Daylight Saving Time, not Daylight SavingS Time.

Saving is used here as a verbal adjective (a participle). It modifies time and tells us more about its nature; namely, that it is characterized by the activity of saving daylight. It is a saving daylight kind of time. Because of this, it would be more accurate to refer to DST as daylight-saving time. Similar examples would be a mind-expanding book or a man-eating tiger. Saving is used in the same way as saving a ball game, rather than as a savings account.

Nevertheless, many people feel the word savings (with an ’s’) flows more mellifluously off the tongue. Daylight Savings Time is also in common usage, and can be found in dictionaries.

Adding to the confusion is that the phrase Daylight Saving Time is inaccurate, since no daylight is actually saved. Daylight Shifting Time would be better, and Daylight Time Shifting more accurate, but neither is politically desirable.

Rationale and original idea

The main purpose of Daylight Saving Time (called “Summer Time” in many places in the world) is to make better use of daylight. We change our clocks during the summer months to move an hour of daylight from the morning to the evening. Countries have different change dates.  A poll conducted by the U.S. Department of Transportation indicated that Americans liked Daylight Saving Time because “there is more light in the evenings / can do more in the evenings.” A 1976 survey of 2.7 million citizens in New South Wales, Australia, found 68% liked daylight saving. Indeed, some say that the primary reason that Daylight Saving Time is a part of many societies is simply because people like to enjoy long summer evenings, and that reasons such as energy conservation are merely rationalizations.

                                         

According to some sources, DST saves energy. Studies done by the U.S. Department of Transportation in 1975 showed that Daylight Saving Time trims the entire country’s electricity usage by a small but significant amount, about one percent each day, because less electricity is used for lighting and appliances. Similarly, in New Zealand, power companies have found that power usage decreases 3.5 percent when daylight saving starts. In the first week, peak evening consumption commonly drops around five percent.

The rationale behind the 1975 study of DST-related energy savings was that energy use and the demand for electricity for lighting homes is directly related to the times when people go to bed at night and rise in the morning. In the average home, 25 percent of electricity was used for lighting and small appliances, such as TVs and stereos. A good percentage of energy consumed by lighting and appliances occurred in the evening when families were home. By moving the clock ahead one hour, the amount of electricity consumed each day decreased.

                                                                 

In the summer, people who rose before the sun rises used more energy in the morning than if DST were not in effect. However, although 70 percent of Americans rose before 7:00 a.m., this waste of energy from having less sunlight in the morning was more than offset by the savings of energy that results from more sunlight in the evening.

In the winter, the afternoon Daylight Saving Time advantage is offset for many people and businesses by the morning’s need for more lighting. In spring and fall, the advantage is generally less than one hour. So, the rationale was that Daylight Saving Time saves energy for lighting in all seasons of the year, but it saves least during the four darkest months of winter (November, December, January, and February), when the afternoon advantage is offset by the need for lighting because of late sunrise.

Reprinted from the web site:  webexhibits.org/daylightsaving

Gary Dobbs, Meteorologist / StormForce 31

The Orionid meteor shower is the second of two showers that occur each year as a result of Earth passing through dust released by Halley’s Comet, with the first being the Eta Aquarids. The point from where the Orionid meteors appear to radiate is located within the constellation Orion.

The Orionids generally begin on October 15 and end on October 29, with maximum generally occurring during the morning hours of October 20-22. The Orionids are barely detectable on the beginning and ending dates, but observers in the Northern Hemisphere will see around 20 meteors per hour at maximum, while observers in the Southern Hemisphere will see around 40 meteors per hour. The maximum can last two or three nights, although there is evidence of some fluctuation from year to year.

There are other, weaker meteor showers going on around the same time as the Orionids. The Orionids generally appear to move fast. When you see a meteor, mentally trace it backwards. If you end up at Orion then you have probably seen an Orionid meteor! If you are not sure where Orion is in the sky, the following chart will help you find it from the Northern Hemisphere:

Location of the Orionids
For Northern Hemisphere Observers

This represents the view from mid-northern latitudes at about 1:00 a.m. local time around October 21. The graphic does not represent the view at the time of maximum, but is simply meant to help prospective observers to find the radiant location. The red line across the bottom of the image represents the horizon.

History

The discovery of the Orionid meteor shower should be credited to E. C. Herrick (Connecticut, USA). In 1839, he made the ambiguous statement that activity seemed to be present during October 8 to 15. A similar statement was made in 1840, when he commented that the “precise date of the greatest meteoric frequency in October is still less definitely known, but it will in all probability be found to occur between the 8th and 25th of the month.”

The first precise observation of this shower was made by A. S. Herschel on 1864 October 18, when fourteen meteors were found to radiate from the constellation of Orion. Herschel confirmed that a shower originated from Orion on 1865 October 20. Thereafter, interest in this stream increased very rapidly—with the Orionids becoming one of best observed annual showers.

The Orionids were frequently observed during the latter years of the 19th century and became the focus of debate during the first quarter of the 20th century. The British amateur astronomer W. F. Denning and the American astronomer C. P. Olivier began using the pages of two astronomical periodicals to debate whether the Orionid radiant, the point from which the meteors seemed to radiate in the sky, moved from one day to the next: Denning argued that it did not, while Olivier argued that it did. Each astronomer had supporters that chimed in, but the argument remained essentially theirs. The problem was that the Orionid radiant was more diffuse than the other well-observed annual meteor showers. Thanks to the use of photography and the very precise plotting of meteors by several amateur and professional astronomers, Oliver was eventually proven correct.

One very unusual feature the Orionids tend to display is an unpredictable maximum. In 1981, observers reported very low rates of less than 10 meteors per hour during the period of October 18 to 21 (maximum predicted for October 21), but high rates of near 20 per hour were noted on the morning of October 23. Interestingly, a study published in Czechoslovakia during 1982, revealed the Orionids generally exhibited a double maximum. The finding was based on observations made during the period spanning 1944 to 1950. Shortly thereafter, several visual studies indicated the presence of a “plateau effect” or a long period of maximum devoid of any sharp decline of activity, instead of a double peak. Most notably, the 1984 observations of the Western Australia Meteor Section, show a nearly flat maximum lasting from October 21 to 24, while N. W. McLeod, III (Florida, USA), has frequently noted it to stretch up to 6 days.

The variation in activity levels around the time of maximum has been attributed to the presence of filaments within the Orionid stream orbit. Each of these filaments represents a previous orbit that comet Halley has followed in the past. Since observations indicate that comet Halley has been around for over 2200 years and since the comet orbits the sun in about 76 years, there are quite a few filaments making up the Orionid stream.

Reprinted from meteorshowers.com

Gary Dobbs, Meteorologist / StormForce 31

It is known as the Little Ice Age. Bitter winters blighted much of the northern hemisphere for decades in the second half of the 17th century. The French army used frozen rivers as thoroughfares to invade the Netherlands. New Yorkers walked from Manhattan to Staten Island across the frozen harbour. Sea ice surrounded Iceland for miles and the island’s population halved. It wasn’t the first time temperatures had plunged: a couple of hundred years earlier, between 1420 and 1570, a climatic downturn claimed the Viking colonies on Greenland, turning them from fertile farmlands into arctic wastelands.

Could the sun have been to blame? We now know that, curiously, both these mini ice ages coincided with prolonged lulls in the sun’s activity – the sunspots and dramatic flares that are driven by its powerful magnetic field.

Now some astronomers are predicting that the sun is about to enter another quiet period. With climate scientists warning that global warming is approaching a tipping point, beyond which rapid and possibly irreversible damage to our environment will be unavoidable, a calm sun and a resultant cold snap might be exactly what we need to give us breathing space to agree and enact pollution controls. “It would certainly buy us some time,” says Joanna Haigh, an atmospheric physicist at Imperial College London.

Global average temperatures have risen by about 0.6 °C in the past century, and until recently almost all of this has been put down to human activity. But that may not be the only factor at work. A growing number of scientists believe that there are clear links between the sun’s activity and the temperature on Earth. While solar magnetic activity cannot explain away global warming completely, it does seem to have a significant impact. “A couple of years ago, I would not have said that there was any evidence for solar activity driving temperatures on Earth,” says Paula Reimer, a palaeoclimate expert at Queen’s University, Belfast, in the UK. “Now I think there is fairly convincing evidence.”

                        

What has won round Reimer and others is evidence linking climate to sunspots. These blemishes on the sun’s surface appear and fade over days, weeks or months, depending on their size. More than a mere curiosity, they are windows on the sun’s mood. They are created by contortions in the sun’s magnetic field and their appearance foretells massive solar eruptions that fling billions of tonnes of gas into space. Fewer sunspots pop up when the sun is calm, and historically these periods have coincided with mini ice ages.

The number of sunspots and solar magnetic activity in general normally wax and wane in cycles lasting around 11 years, but every 200 years or so, the sunspots all but disappear as solar activity slumps (see “Field feedback”). For the past 50 years, on the other hand, the sun has been particularly restless. “If you look back into the sun’s past, you find that we live in a period of abnormally high solar activity,” says Nigel Weiss, a solar physicist at the University of Cambridge.

Fortunately, an indirect record of the sun’s moods stretching back thousands of years has been preserved on Earth in the concentrations of rare isotopes locked into tree rings and ice cores. The story begins way out beyond the orbit of Pluto, at the boundary of the sun’s magnetic field. While the sun is magnetically calm, its field extends around 12 billion kilometres into space, but the field puffs up to 15 billion kilometres when the sun is active. Cosmic rays – the high-energy particles from deep space that are constantly hurtling towards us – are deflected by the field, so at active times far fewer of them reach the Earth.

Cosmic correlation

The rays that do reach our planet leave traces in the form of carbon-14 and beryllium-10, isotopes that are only created when cosmic rays slam into the Earth’s atmosphere. Plants and trees then absorb carbon-14, while beryllium-10 settles onto the polar ice sheets and becomes incorporated into that year’s ice layer. So by measuring the levels of the isotopes in tree rings and polar ice cores, we can work out how many cosmic rays were reaching Earth when the rings or ice layers were formed, and so estimate how active the sun was at those times.

Sami Solanki and his team at the Max Planck Institute for Solar System Research in Katlenburg-Lindau, Germany, have looked at the concentrations of carbon-14 in wood and beryllium-10 in ice as far back as back 11,000 years ago. The similarity of the fluctuations in both isotopes convinced them that they were seeing effects due to the sun. The peaks and slumps showed a recognisable pattern: “Periods of high solar activity do not last long, perhaps 50 to 100 years, then you get a crash,” says Weiss. “It’s a boom-bust system, and I would expect a crash soon.”

Although another crash is likely, predicting the sun’s activity with any certainty is difficult because of the chaotic way in which the solar magnetic field is generated. If anyone can do it, though, it’s solar physicist turned computer programmer Leif Svalgaard, from Stanford University in California, who has been forecasting solar activity for nearly three decades. In the 1970s, he pioneered the best forecasting method yet devised, which uses the strength of the magnetic field at the sun’s poles to predict future levels of solar activity.

He too expects a crash. The sun’s polar field is now at its weakest since measurements began in the early 1950s, and to Svalgaard, the latest figures indicate that the sun’s activity will be weaker during the next decade than it has been for more than 100 years. “Sunspot numbers are well on the way down in the next decade,” he predicts. He expects fewer than six new sunspots per month, less than half the average number seen over the past decade.

This is hardly the sunspot crash that observations from 1645 to 1715 suggest. Back then, the appearance of even a single sunspot was major astronomical news, sparking hurriedly penned communications from one observatory to another. Nevertheless, it’s a sign of things to come. “Sunspot numbers will be extremely small, and when the sun crashes, it crashes hard,” says Svaalgard.

Hot link

So what does the sun’s magnetic activity have to do with the climate on Earth? To pin down the connection, Solanki and his colleagues compared records of solar activity derived from tree rings with meteorological records from 1856 to the present day. They found that the temperature of the Earth’s atmosphere changed in step with sunspot numbers until 1970. This is the evidence that has done more than anything else to convince climatologists to take the link seriously. What’s more, the most recent calculations by Solanki’s team suggest that the sunspot crash could lead to a cooling of the Earth’s atmosphere by 0.2 °C. It might not sound much, but this temperature reversal would be as big as the most optimistic estimate of the results of restricting greenhouse-gas emissions until 2050 in line with the Kyoto protocol.

There is still a big puzzle, though. Astronomers and climate scientists have always struggled to understand exactly how solar activity could influence the temperature on Earth. Whatever the variations in the sun’s magnetic activity, the total energy it emits changes by only 0.1 per cent – too small a change to have any direct effect. As a result, the sun’s role in climate change is highly controversial. “People have been arguing over this for years,” says Reimer.

What other factor is at work? Important clues have emerged recently from solar observatories, including the SOHO spacecraft operated by NASA and the European Space Agency for the past 10 years. Although the change in overall solar energy is small, measurements made by SOHO and other solar observatories have revealed much greater variation in the levels of ultraviolet radiation, which can peak at up to 100 times its minimum level. “This means that there is scope for ultraviolet to have a much larger effect on our atmosphere,” says Haigh, who for the past decade has been studying the impact of the sun’s variability on climate.

According to computer models she has developed, ultraviolet radiation heats the upper reaches of the Earth’s atmosphere by energising atoms and molecules there. This drives chemical reactions involving ozone and other molecules, which can release still more heat. This heating changes the temperature structure of the atmosphere at all altitudes, although the details are unclear because of the sheer complexity of Haigh’s model. “By varying the amount of ultraviolet radiation, solar activity changes the circulation of the whole atmosphere,” she says. Change the circulation, and you change the weather.

Haigh’s work may help to explain one of the most puzzling aspects of the Little Ice Age: “Europe was badly hit, but other parts of the world may not really have noticed it,” says Solanki. This might have been due to the different distribution of land masses in the northern and southern hemispheres. While Antarctica is surrounded by a wide belt of ocean, the distribution of land and oceans in the northern hemisphere is much less regular. This means that the interaction between the circulating atmosphere and the ground is more complex in the northern hemisphere. It gives rise to the North Atlantic Oscillation, an interplay of low and high pressure that dictates the movement of storms across the continents bordering the north Atlantic.

Haigh has found that at times of low solar activity the air pressure over the North Pole is higher than normal and forces storms south, funnelling colder weather to lower latitudes. What happens in the southern hemisphere is less well known, but Haigh says she wouldn’t be surprised if the reaction here to changes in solar activity is different.

Solar activity might also influence climate through its effect on cosmic rays. In another study, Solanki has found an intriguing correlation between the temperature of the Earth’s atmosphere and the number of cosmic rays striking it, with lower temperatures in periods of high numbers of cosmic rays.

How could cosmic rays lead to cooler temperatures? Enter a theory proposed by Henrik Svensmark and Eigil Friis-Christensen of the Danish Meteorology Institute in Copenhagen almost a decade ago. They suggested that cosmic rays create an electric charge in particles in our atmosphere that then act as seeds for the formation of clouds at low altitudes. A spell of low solar activity would mean more cosmic rays and therefore more clouds and lower temperatures.

Svensmark and Friis-Christensen’s idea is controversial, however (New Scientist, 11 July 1998, p 45). Most climatologists accept that more low clouds would reflect more radiation back into space, thus lowering temperatures. But many dismiss Svensmark and Friis-Christensen’s evidence of a link between cosmic rays and cloud cover as coincidence (see “Cloud cover”). Others want the theory investigated, if only to rule it out. To this end, an international group of more than 50 scientists have proposed an experiment at the CERN particle physics laboratory near Geneva, Switzerland, to begin in 2008.

No room for complacency

The coming years could settle the sun’s role on temperatures once and for all. If the expected sunspot crash does takes place, Solanki’s work could receive dramatic confirmation. “Having a crash would certainly allow us to pin down the sun’s true level of influence on the Earth’s climate,” says Weiss.

None of this means that we can stop worrying about global warming caused by emissions into the atmosphere. “The temperature of the Earth in the past few decades does not correlate with solar activity at all,” Solanki says. He estimates that solar activity is responsible for only 30 per cent, at most, of the warming since 1970. The rest must be the result of man-made greenhouse gases, and a crash in solar activity won’t do anything to get rid of them.

What might happen is that the sun gives the planet a welcome respite from the ravages of man-made climate change – though for how long, nobody knows. During the Little Ice Age, the fall in average global temperature is estimated to have been less than 1 °C and lasted 70 years. The one before that persisted for 150 years, but a minor crash at the beginning of the 19th century lasted barely 30. For now, we will have to keep watching for falling sunspot numbers. “The deeper the crash, the longer it will last,” Weiss says.

There is a dangerous flip side to this coin. If global warming does slow down or partially reverse with a sunspot crash, industrial polluters and reluctant nations could use it as a justification for turning their backs on pollution controls altogether, makingmatters worse in the long run. There is no room for complacency, Svalgaard warns: “If the Earth does cool during the next sunspot crash and we do nothing, when the sun’s magnetic activity returns, global warming will return with a vengeance.”

Reprinted from:

http://environment.newscientist.com

Gary Dobbs, Meteorologist / StormForce 31

After that previous post on archaeoastronomy, I thought it time to write something from a more scientific viewpoint.  Of course, I’m talking about the science of woollywormology. 

Do Woolly Worms Know Something That We Don’t?

Can woolly worms forecast winter weather? Folklore has it that woolly worms are really miniature weather forecasters. Careful observation of these short, fuzzy caterpillars in the fall supposedly can tell you what kind of weather the coming winter will hold.

The woolly worms of winter weather forecasting fame are black at each end with a reddish brown band in the middle. The size of the brown band is said to be an indicator of winter’s severity. The narrower the band, the harsher the winter. If woolly worms are more brown than black and the middle band tends toward orange, that indicates the winter will be mild.

Well, that’s a fun bit of folk wisdom, but it’s simply not true. The experts at the West Virginia University Extension Service say there is no scientific evidence suggesting that woolly worms can predict the weather.

Woolly worm is a common name for the larval stage of the Isabella tiger moth. The scientific name for this insect is Pyrrhactia isabella. Other common names for this caterpillar are woolly bears, black-ended bears and banded woolly bears (the name approved by the Entomological Society of America).

Woolly worms grow from 1-3 inches long and are found throughout the United States. The West Virginia University scientists say variations in their bands are linked to differences in species and larval stage, not the weather.

The genus Pyrrhactia includes many different species. Some are solid black, without any bands and others have bands of varying sizes. Woolly worms go through six larval stages before entering their pupal or winter cocoon stage. In other words, the caterpillar molts six times and the color and size of its bands may change from molt to molt.

So, woolly worms cannot be counted on to provide a peek at what the coming winter holds. Still, this fall’s woolly worms will become next spring’s moths. And that in itself is a pretty amazing feat.

Some of the popular woolly worms actually turn into spring’s monarch butterflies.

So, watch for those woolly worms during October and see if they can forecast winter better than Brad, Keller or me. 

Gary Dobbs, Meteorologist / StormForce 31