03.03.2015
Definition of Electromagnetic spectrumFor convenience in talking about electromagnetic radiation, we classify photons of different energies into different spectral regions. Although non-ionizing radiation has lower energy, too much of it may still affect our health, e.g.
Though the sun lies 93 million miles (149 million km) from Earth, its unceasing activity assures an impact on our planet far beyond the obvious light and heat. Studying the surface of the sun can reveal small, dark areas that vary in number and location.
Similarly, sunspots might seem small when compared to the 865,000-mile (1.392 million kilometers) diameter of the sun, because they typically cover less than 4 percent of its visible disk. Scientists measure the activity of the sun by keeping track of the number of sunspots appearing on its surface. This snapshot from NASA's Solar Dynamics Observatory shows a stunning prominence associated with a Sept.
The high magnetic fields in the sunspot-producing active regions also give rise to explosions known as solar flares. Temperatures in the outer layer of the sun, known as the corona, typically fall around a few million kelvins.
Because solar flares form in the same active regions as sunspots, they are connected to these smaller, less violent events. When the energized particles exploding from solar flares race toward us, they arrive in only eight minutes.
This still from SDO caught the action in freeze-frame splendor when the Sun popped off two events at once (Jan.
The magnetic field lines that twist up to form solar flares occasionally become so warped that, like rubber bands under tension, they snap and break, then reconnect at other points. It takes several hours for the CME to detach itself from the sun, but once it does, it races away at speeds of up to 1,000 km (more than 7 million miles per hour). The cloud of hot plasma and charged particles may be up to 100 billion kilograms (220 billion pounds) in size.
As with solar flares, if the CME is aimed in our direction, it takes the particles eight minutes to reach Earth. The northern lights are more formally known as auroras, and are caused by interactions between the solar wind and the Earth's magnetic field.
However, when the sun does eject a cloud of plasma and gas directly toward us, the incoming matter seems to surround the sun. Like solar flares, CMEs bring an increase in radiation to astronauts and electronics in space. A ULA Atlas 5 rocket carrying NASA’s Solar Dynamics Observatory satellite rolls out to its Space Launch Complex-41 launch pad at Cape Canaveral Air Force Station in Fla., for a planned Feb. Se l'esposizione al sole continua, dopo qualche giorno gli UVB provocano una colorazione progressiva, responsabile della vera e propria abbronzatura. L'intensità degli UVA che raggiungono la superficie terrestre rimane praticamente costante durante l'anno.
Il fatto che l'organismo sia esposto ai raggi UVA durante tutto l'arco dell'anno e che proprio queste radiazioni siano responsabili del photo-aging, suggerisce l'importanza di una protezione cutanea a 360 gradi. Le reazioni della cute nei confronti delle radiazioni solari dipendono dal fototipo del soggetto (gli individui di pelle chiara sono più sensibili) e dal numero di fototraumi subiti fin dall'infanzia. L'abbronzatura artificiale (lampade solari) comporta lo stesso rischio di danni acuti e cronici, rispetto ai raggi UV provenienti dalla sorgente naturale.
The photons in all of these regions have the same electromagnetic nature, but because of their very different energies they interact with matter very differently. 13th at 1738 UT, sunspot 1158 unleashed the strongest solar flare of the year so far, an M6.6-category X-ray irradiance magnitude blast. From a constant stream of particles in the form of solar wind to the unpredictable bombardment from solar flares and coronal mass ejections, Earth often feels the effects of its stellar companions. However, ranging from 1,500 miles to 30,000 miles (2,500-50,000 km) in size, they can reach the width of the planet Neptune, the smallest of the gas planets.


As it reaches the close of a cycle, new sunspots appear near the equator, while a new cycle produces sunspots in higher latitudes. The 11-year cycle began in January 2008 and peaked in 2013, the weakest solar maximum in 100 years, according to NASA. When the twisted field lines cross and reconnect, energy explodes outward with a force exceeding that of millions of hydrogen bombs. As solar flares push through the corona, they heat its gas to anywhere from 10 to 20 million K, occasionally reaching as high as a hundred million.
They can cause long-lasting radiation storms in the upper atmosphere, and trigger radio blackouts.
The bright emission of the surrounding photosphere, where the sun's light originates, tends to overshadow even these explosive phenomena. However, the particles take anywhere from one to five days to travel the distance to our planet. At the high point of the solar cycle, the sun may produce as many as five CMEs in a given day; even at the low point, it averages one a day. But unlike flares, they also bring charged particles of matter that interact with the field surrounding our planet. 1, 1859, Richard Carrington and Richard Hodgson, both amateur English astronomers, independently made the first observations of a solar flare, one that resulted in the largest geomagnetic storm ever recorded. This allows satellites and power transformers to be shut down if necessary for a short period of time. She loves all things space and astronomy-related, and enjoys the opportunity to learn more. Quando colpiscono l'organismo non riescono a superare lo strato più superficiale della cute, detto epidermide. Rispetto agli UVB sono più penetranti, non provocano ustioni e non abbronzano realmente.
Questo fenomeno è responsabile della precoce insorgenza di un lieve imbrunimento, che compare dopo poche ore dalla prima esposizione solare estiva.
Le creme protettive andrebbero infatti applicate non solo d'estate, ma in qualsiasi occasione in cui ci si esponga alla luce solare. E' fondamentale tenere in considerazione che il melanoma può derivare dalla trasformazione maligna di un neo benigno.
For example, the human eye can only detect radiation that is in the visible region of the spectrum (hence the name).
NASA's Solar Dynamics Observatory recorded an intense flash of extreme ultraviolet radiation. Less noticeable are the sunspots crossing the solar surface, though they are related to the more violent interactions.
If a single sunspot stood alone in the night sky, it would be 10 times brighter than the full moon. But with a lifetime of anywhere from a few days to a few weeks, sunspots are far less permanent. The cycles overlap; sunspots from the previous cycle can still develop even after sunspots from the new cycle appear. Despite the low level of activity, one of the largest sunspot regions ever was observed in November 2014, reaching approximately the size of Jupiter. In 1849, astronomers at the Zurich Observatory began observing and counting sunspots on a daily basis. At the peak of the cycle, several flares may occur each day, with an average lifetime of only 10 minutes. Medium-size M-class flares can cause brief radio blackouts in the polar regions and the occasional minor radiation storms. A filament on the left side became unstable and erupted, while an M-1 flare (mid-sized) and a coronal mass ejection on the right blasted into space.
The solar wind, a constant stream of charged particles ejected by the sun, acts on the cloud like a current on a boat.


Long metal structures like oil and gas pipelines can carry currents, which can enhance their corrosion over time and lead to devastating effects if proper safety measures are not in place.
The result is a short- term, controlled blackout rather than a longer one caused by the destruction of vital equipment.
Tuttavia, in virtù della forte carica energetica, i raggi UVB sono piuttosto aggressivi e stimolano l'abbronzatura. In compenso, proprio per la loro capacità di penetrare fino al derma, accelerano i processi di invecchiamento cutaneo.
Il primo colpisce le cellule basali dell'epidermide, si manifesta in aree cutanee scoperte, è maligno ma rimane circoscritto (non causa metastasi). Quindi, specialmente se i nei vengono tormentati manualmente, si può avere una trasformazione neoplastica molto pericolosa. These photons are both transmitted by the lens of the human eye and absorbed by the photoreceptors in the retina.
Most of the rope, or filament, lies inside the sun, but part of it may break through the visible layer, where it is viewed in the form of two sunspots. As the solar cycle progresses, new sunspots appear closer to the equator, with the last of them appearing at an average latitude of 5 to 10 degrees. So solar scientists have a very difficult time saying exactly when one cycle ends and the next begins.
Similarly, satellites previously circling through vacuum-free space can find themselves caught in the expanded sphere. However, since X-rays and gamma rays fail to penetrate the atmosphere, only space-based telescopes can detect their signatures. Faster CMEs feel the drag of the wind and slow down, while those with low initial velocities speed up.
While lightning lasts on the order of microseconds, however, the magnetic storm created lasts far longer. The resulting variations in the ionosophere can disrupt GPS signals, giving inaccurate readings. These programs will help bring a greater understanding of the subject of space weather on Earth. Soltanto se viene trascurato, con il passare del tempo può espandersi ai tessuti circostanti.
Ancora una volta la raccomandazione principale è di tenere sotto controllo lo stato dei propri nei, tenendo presente che quando questi si trasformano in melanoma, assumono contorni irregolari e sfumature di vario colore. There is no fundamental difference in the nature of electromagnetic radiation of 350 nm versus 400 nm, other than our eyes can sense the 400-nm photons directly.
The pair are polar opposites, literally; think of them as magnetic north and south, with the rope acting as the magnet in between.
The resulting friction slows down their orbit, and can bring them back to Earth sooner than intended. Even after unhooking them from the power supply, messages could still be transmitted, powered by the currents in the atmosphere. Some of the boundaries between spectral regions are not well-defined as between ultraviolet and visible radiation. Visible SpectrumThe visible region of the electromagnetic spectrum consists of photons with wavelengths from approximately 400 to 700 nm.
The short wavelength cutoff is due to absorption by the lens of the eye and the long wavelength cutoff is due to the decrease in sensitivity of the photoreceptors in the retina for longer wavelengths.
Electromagnetic SpectrumThe following table lists the names of different spectral regions, the range of frequencies and wavelengths in those regions, and the type of transition that can occur when a photon in these spectral ranges interacts with matter.



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Comments Ultraviolet light definition physics

  1. ele_bele_gelmisem
    Polymer with an optical clarity that could adhesive.
  2. Lizok
    Light, in the form of a laser emits UV-C but it is absorbed.