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Space Weather Prediction Center

National Oceanic and Atmospheric Administration

Tuesday, September 02, 2014 21:14:03

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NOAA Scales mini

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Space Weather Conditions
R
no data
S
no data
G
no data
R
no data
S
no data
G
no data
Yesterday
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no data
S
no data
G
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Today's Max Observed
R
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S
no data
G
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Now
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no data
S
no data
G
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Predicted: Rest of Today
R1-R2 --
R3-R5 --
S1 or greater --
G
no data
Tomorrow
R1-R2 --
R3-R5 --
S1 or greater --
G
no data
R1-R2 --
R3-R5 --
S1 or greater --
G
no data
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R
no data
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Current Space Weather Conditions
R1 (Minor) Radio Blackout Impacts
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HF Radio: Weak or minor degradation of HF radio communication on sunlit side, occasional loss of radio contact.
Navigation: Low-frequency navigation signals degraded for brief intervals.
More about the NOAA Space Weather Scales

Sunspots/Solar Cycle

Sunspots/Solar Cycle
Sunspots/Solar Cycle

Sunspots are dark regions on the sun. They are regions of intense magnetic field where solar flares and the most significant coronal mass ejections occur. Sunspots appear dark on the sun’s surface because they are cooler (3700 K) than the rest of the solar surface (6000 K). Sunspots are cooler because they have very intense magnetic fields that inhibit the rise of heat from the solar interior. Sunspots can appear alone, or in close connection to other sunspots. Sunspots that are clearly connected to each other are grouped into active regions with an official number designated by NOAA. Active regions are then classified according to their size and complexity with a scale known as the modified Zurich scale. Though they appear dark to the naked eye, if one were to see the Sun in ultra violet or x-rays, then sunspots and active regions would appear brighter than the other areas of the Sun. The energy that sunspots lack in heat is made up instead by the energy of the magnetic field. The magnetic fields rise above the surface, staying strong, where the rest of the sun has weak magnetic fields. The strong magnetic fields form into loops that hold in solar plasma and heat it to extreme temperatures in excess of 1 million K. At these temperatures, we can’t see the plasma in visible light, but it becomes the dominant feature in ultra violet and x-rays. These magnetic fields are the main source of most of space weather, as changes in sunspot magnetic fields cause solar flares (Radio Blackouts) and the fastest coronal mass ejections.

Sunspots change continuously but individual spots may persist for only a few hours or for many weeks. The total number of sunspots has long been known to vary with an 11 year period, known as the solar cycle. The peak of the solar cycle is known as solar maximum and the valley of the cycle is known as solar minimum. At solar minimum there can be many days in a row with absolutely no sunspots visible, while at solar maximum hundreds of spots may be visible at any time. Solar cycles are numbered with solar cycle 1 beginning in 1755 and the most recent solar cycle, cycle 24, began in December, 2008. Counting of sunspot numbers is a bit tricky, because not only does each sunspot count as 1, but each active region counts as 10. Because a lone sunspot is also considered an active region, it is counted as 11, so on a given day, the sunspot number can be 0, 11, or any number greater than 11.

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