26-30 May 2021. What's the difference between a CME, solar flare?
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Background.
Solar cycle 25 is recognized as having started in November. A solar cycle is marked by increased sunspot appearance and activity.
Leading-up to November, our sun had been active in tossing-out coronal mass. Although it is predicted that this solar cycle is not going to be overall very active (relative to past cycles); we have already seen a marked increase in activity, even before this one officially began.
As we head into Cycle #25, we are seeing increased solar activity. A variety of interesting phenomena is occurring, It's important to understand the basic vocabulary.
This video comes as a result of conversation in the chats of Wage's World livestreams, in amongst other places.
There is an accompanying video that explains some of the accompanying phenomena.
If we are identifying a solar cycle based on the prevalence of sunspots, it would be nice to know what one is.
Before this, it might be nice to know what a sunspot is...
Little introduction to this video. This is a reading of material I've collected from online. I needed to provide a common vocabulary (lexicon) of phrases, first and foremost, as the time is running short. This is simply the spoken text. a livestream is intended to show the images that would otherwise accompany this work.
Keywords: solar cycle, cme, solar flare, solar wind, plasma, magnetic field, .
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- CME: What is a Coronal Mass Ejection (CME)?
" Coronal Mass Ejections (CMEs) are large expulsions of plasma and magnetic field from the Sun’s corona.
" They can eject billions of tons of coronal material and carry an embedded magnetic field (frozen in flux) that is stronger than the background solar wind interplanetary magnetic field (IMF) strength.
" CMEs travel outward from the Sun at speeds ranging from slower than 250 kilometers per second (km/s) to as fast as near 3000 km/s.
" The fastest Earth-directed CMEs can reach our planet in as little as 15-18 hours.
" Slower CMEs can take several days to arrive.
" They expand in size as they propagate away from the Sun and larger CMEs can reach a size comprising nearly a quarter of the space between Earth and the Sun by the time it reaches our planet.
" The more explosive CMEs generally begin when highly twisted magnetic field structures (flux ropes) contained in the Sun’s lower corona become too stressed and realign into a less tense configuration – a process called magnetic reconnection.
" This can result in the sudden release of electromagnetic energy in the form of a solar flare; which typically accompanies the explosive acceleration of plasma away from the Sun – the CME.
" These types of CMEs usually take place from areas of the Sun with localized fields of strong and stressed magnetic flux; such as active regions associated with sunspot groups.
" CMEs can also occur from locations where relatively cool and denser plasma is trapped and suspended by magnetic flux extending up to the inner corona - filaments and prominences.
" When these flux ropes reconfigure, the denser filament or prominence can collapse back to the solar surface and be quietly reabsorbed, or a CME may result.
" CMEs travelling faster than the background solar wind speed can generate a shock wave.
" These shock waves can accelerate charged particles ahead of them – causing increased radiation storm potential or intensity.
" Important CME parameters used in analysis are size, speed, and direction.
" These properties are inferred from orbital satellites’ coronagraph imagery by SWPC forecasters to determine any Earth-impact likelihood.
" The NASA Solar and Heliospheric Observatory (SOHO) carries a coronagraph – known as the Large Angle and Spectrometric Coronagraph (LASCO).
" This instrument has two ranges for optical imaging of the Sun’s corona: C2 (covers distance range of 1.5 to 6 solar radii) and C3 (range of 3 to 32 solar radii).
" The LASCO instrument is currently the primary means used by forecasters to analyze and categorize CMEs; however another coronagraph is on the NASA STEREO-A spacecraft as an additional source.
" Imminent CME arrival is first observed by the Deep Space Climate Observatory (DSCOVR) satellite, located at the L1 orbital area.
" Sudden increases in density, total interplanetary magnetic field (IMF) strength, and solar wind speed at the DSCOVR spacecraft indicate arrival of the CME-associated interplanetary shock ahead of the magnetic cloud.
" This can often provide 15 to 60 minutes advanced warning of shock arrival at Earth – and any possible sudden impulse or sudden storm commencement; as registered by Earth-based magnetometers.
" Important aspects of an arriving CME and its likelihood for causing more intense geomagnetic storming include the strength and direction of the IMF beginning with shock arrival, followed by arrival and passage of the plasma cloud and frozen-in-flux magnetic field.
" More intense levels of geomagnetic storming are favored when the CME enhanced IMF becomes more pronounced and prolonged in a south-directed orientation.
" Some CMEs show predominantly one direction of the magnetic field during its passage, while most exhibit changing field directions as the CME passes over Earth. Generally, CMEs that impact Earth’s magnetosphere will at some point have an IMF orientation that favors generation of geomagnetic storming.
" Geomagnetic storms are classified using a five-level NOAA Space Weather Scale.
" SWPC forecasters discuss analysis and geomagnetic storm potential of CMEs in the forecast discussion and predict levels of geomagnetic storming in the 3-day forecast."
Source: NOAA; published: Tuesday, February 02, 2021 16:41 UTC [1). -link below].
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- Solar Flare: What is a 'solar flare' ?
" A solar flare is an intense burst of radiation coming from the release of magnetic energy associated with sunspots. Flares are our solar system’s largest explosive events. They are seen as bright areas on the sun and they can last from minutes to hours.
" We typically see a solar flare by the photons (or light) it releases, at most every wavelength of the spectrum. The primary ways we monitor flares are in x-rays and optical light.
" Flares are also sites where particles (electrons, protons, and heavier particles) are accelerated."
Source: NASA; Editor: Holly Zell ; Last Updated: Aug 7, 2017 [2). -link below]
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- Solar Flare
" A solar flare is basically a giant explosion on the surface of our Sun which occurs when magnetic field lines from sunspots tangle and erupt.
A solar flare is defined as a sudden, rapid, and intense variation in brightness.
A solar flare occurs when magnetic energy that has built up in the solar atmosphere is suddenly released.
Material is heated to many millions of degrees in just minutes and radiation is emitted across virtually the entire electromagnetic spectrum, from radio waves at the long wavelength end, through optical emission to X-rays and gamma rays at the short wavelength end.
The amount of energy released is equivalent to millions of nuclear bombs exploding all at the same time!
Solar flares are an often occurrence when the Sun is active in the years around solar maximum.
Many solar flares can occur on just one day during this period!
Around solar minimum, solar flares might occur less than once per week.
Large flares are less frequent than smaller ones.
Some (mostly stronger) solar flares can launch huge clouds of solar plasma into space which we call a coronal mass ejection.
When a coronal mass ejection arrives at Earth, it can cause a geomagnetic storm and intense auroral displays.
- The classification of solar flares
Solar flares are classified as A, B, C, M or X according to the peak flux (in watts per square metre, W/m2) of 1 to 8 Ångströms X-rays near Earth, as measured by XRS instrument on-board the GOES-15 satellite which is in a geostationary orbit over the Pacific Ocean.
The table below shows us the different solar flare classes:
Class W/m2 between 1 & 8 Ångströms
A <10-7
B ≥10-7 <10-6
C ≥10-6 <10-5
M ≥10-5 <10-4
X ≥10-4
Each X-ray class category is divided into a logarithmic scale from 1 to 9.
For example: B1 to B9, C1 to C9, etc. An X2 flare is twice as powerful as an X1 flare, and is four times more powerful than an M5 flare.
The X-class class category is slightly different and doesn’t stop at X9 but continues on.
Solar flares of X10 or stronger are sometimes also called “Super X-class solar flares.”
- A & B-class solar flares
" The A & B-class are the lowest class of solar flares. They are very common and not very interesting.
The background flux (amount of radiation emitted when there are no flares) is often in the B-range during solar maximum and in the A-range during solar minimum.
- C-class solar flares
" C-class solar flares are minor solar flares that have little to no effect on Earth.
Only C-class solar flares which are long in duration might produce a produce a coronal mass ejection but they are usually slow, weak and rarely cause a significant geomagnetic disturbance here on Earth.
The background flux (amount of radiation emitted when there are no flares) can be in the lower C-class range when a complex sunspot region inhabits the Earth-facing solar disk.
- M-class solar flares
M-class solar flares are what we call the medium large solar flares. They cause small (R1) to moderate (R2) radio blackouts on the daylight side of the Earth.
Some eruptive M-class solar flares can also cause solar radiation storms.
Strong, long duration M-class solar flares are likely candidates to launch a coronal mass ejection.
If the solar flare takes place near the center of the Earth-facing solar disk and launches a coronal mass ejection towards our planet, there is a high probability that the resulting geomagnetic storm is going to be strong enough for aurora on the middle latitudes.
- X-class solar flares
X-class solar flares are the biggest and strongest of them all. On average, solar flares of this magnitude occur about 10 times a year and are more common during solar maximum than solar minimum.
Strong to extreme (R3 to R5) radio blackouts occur on the daylight side of the Earth during the solar flare.
If the solar flare is eruptive and takes place near the center of the Earth-facing solar disk, it could cause a strong and long lasting solar radiation storm and release a significant coronal mass ejection that can cause severe (G4) to extreme (G5) geomagnetic storming at Earth.
- So what’s above X9?
The X-class continues after X9 instead of getting a new letter and these solar flares are often referred to as ‘’Super X-class’’ solar flares.
Solar flares that reach or even surpass the X10 class are however very rare and occur only a few times during a solar cycle.
It is actually a good thing that these powerful solar flares do not occur so often as the consequences on Earth could be severe.
The coronal mass ejections which can be launched by such solar flares are known to be able to cause issues with our modern technology like satellites and power lines.
One thing to note with super X-class flares is that an X20 solar flare is not 10 times as strong as an X10 solar flare.
An X10 solar flares equals an X-ray flux of 0.001 Watts/m2 while an X20 solar flare equals 0.002 Watts/m2 in the 1-8 Ångstrom wavelength.
The largest solar flare ever recorded since satellites started to measure them in 1976 was estimated to be an X28 solar flare which occurred on November 4th, 2003 during Solar Cycle 23.
The XRS long channel on the GOES-12 satellite was saturated at X17 for 12 minutes by the intense radiation.
A later analysis of the available data yield an estimated peak flux of X28 however there are scientists who think that this solar flare was even stronger than X28.
A good thing for us was that the sunspot group which produced this solar flare had already rotated largely of the Earth-facing solar disk when the X28 solar flare occurred.
A thing to note is that there has not been a solar flare that saturated the XRS channels on GOES-15 as of March 2017 but it is expected that it will saturate at about the same flux levels.
- High Frequency (HF) radio blackouts caused by solar flares
Bursts of X-ray and Extreme Ultra Violet radiation which are emitted during solar flares and can cause problems with High Frequency (HF) radio transmissions on the sunlit side of the Earth and are most intense at locations where the Sun is directly overhead.
It is mostly High Frequency (HF) (3-30 MHz) radio communication that is affected during such events, although fading and diminished reception may spill over to Very High Frequency (VHF) (30-300 MHz) and higher frequencies.
These blackouts are a result of enhanced electron densities in the lower ionosphere (D-layer) during a solar flare which causes a large increase in the amount of energy radio waves lose when it passes trough this layer.
This process prevents the radio waves from reaching the much higher E, F1 and F2 layers where these radio signals normally refract and bounce back to Earth.
Radio blackouts caused by solar flares are the most common space weather events to affect Earth and also the fastest to affect us.
Minor events occur about 2000 times each solar cycle.
The electromagnetic emission produced during flares travels at the speed of light taking just over 8 minutes to travel from the Sun to Earth.
These type of radio blackouts can last from several minutes to several hours depending on the duration of the solar flare.
How severe a radio blackout is depends on the strength of the solar flare.
The Highest Affected Frequency (HAF) during an X-ray radio blackout during local noon is based on the current X-ray flux value between the 1-8 Ångström.
The Highest Affected Frequency (HAF) can be derived by a formula.
Below you will find a table where you can see what the Highest Affected Frequency (HAF) is during a specific X-ray flux.
GOES X-ray class & flux Highest Affected Frequency
M1.0 (10-5) 15 MHz
M5.0 (5×10-5) 20 MHz
X1.0 (10-4) 25 MHz
X5.0 (5×10-4) 30 MHz
- R-scale
NOAA uses a five-level system called the R-scale, to indicate the severity of a X-ray related radio blackout.
This scale ranges from R1 for a minor radio blackout event to R5 for an extreme radio blackout event, with R1 being the lowest level and R5 being the highest level.
Every R-level has a certain X-ray brightness associated with it. This ranges from R1 for a X-ray flux of M1 to R5 for a X-ray flux of X20.
On Twitter we provide alerts as soon as a certain radio blackout threshold has been reached.
Because each blackout level represents a certain GOES X-ray brightness, you can associate these alerts directly with a solar flare that is occurring at that moment.
We can define the following radio blackout classes:
Source: SpaceWeatherLive.com [3). -link below].
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- Source links:
[1). (https://www.swpc.noaa.gov/news/what-coronal-mass-ejection-cme)]
[2). (https://www.nasa.gov/content/goddard/what-is-a-solar-flare)]
[3). (https://www.spaceweatherlive.com/en/help/what-are-solar-flares.html)]
schumann-resonances web link: (
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