NOAA / Space Weather Prediction Center

SWPC Frequently Asked Questions

General Space Weather | Effects on Earth | Noaa Space Weather Scales | ACE Real-Time Solar Wind


Effects on Earth Systems

1. I'd like to know what impact mass coronal ejections and solar flares have on Earth's weather conditions.

Large solar flares produce x-ray emissions. This can have an effect on minor constituents of the upper atmosphere (<60 km) such as Nitric Oxide (NO). If the conditions were to last long enough, the NO could affect middle atmospheric species such as Ozone but this is highly speculative and very unlikely. CMEs produce large changes in the magnetosphere. This will, in turn, affect the ionosphere. It is unlikely that these effects can propagate down to the lower atmospheric weather.

There is a theory that says that changes in the solar wind will affect the influx of cosmic rays. These cosmic rays might be related to cloud formation and precipitation. NASA has funded research into this area but I must emphasize that it is highly speculative and not widely accepted in the scientific community. The only person really doing this sort of research is Brian Tinsley and if you were to do a reference search on him, you would find the latest on this particular branch of research.

If there is a connection between short term solar activity and weather, it is going to be very small and difficult to measure. Furthermore, the physics behind such a connection would be highly speculative. I should think that the troposphere has a significant amount of inertia and the response times to changes in solar input would be fairly long. Flares and CMEs are short lived events and would therefore, not cause measurable changes in the weather.

There is quite a bit of evidence that changes in solar activity do have measurable affects on weather. The correlation between the temperature at specific locations and the 11 year solar cycle are sometimes quite strong. Karen Labitske in Germany has done a lot of research in this area. The physics is still highly speculative at this point though.

One reference that might be helpful is a NASA publication called Sun, Weather, and Climate by J. R. Herman and R. A. Goldberg. NASA SP-426.-RV


2. Is there a relationship between solar events and earthquakes?

An international meeting of scientists was convened in London from November 7 to 8, 1996, on the subject of relationships of earthquakes to other phenomena for prediction purposes. Papers of that meeting appeared in the Geophysical Journal International, vol. 131, pgs. 413 to 533, 1997. (Perhaps you should read those articles and the summary by Geller). The consensus of the meeting was that prediction was not possible. As Main points out in Nature (vol 385, pg 19-20, 1997) "Modern theories of earthquakes hold that they are critical, or self-organized critical, phenomena, implying a system maintained permanently on the edge of chaos, with an inherently random element and avalanche dynamics with strong sensitivity to small stress perturbations."

Geller, a prominent seismologist at the University of Tokyo who continues to research the possible earthquake relationships to other natural phenomena, reports "The chaotic, highly nonlinear nature of the earthquake source process makes prediction and inherently unrealizable goal." If you believe that you have some solid firsthand evidence, perhaps you should write to Geller to bring yourself up-to-date on this subject (Dr. Robert, Dept. of Earth and Planetary Physics, Graduate School of Science, Tokyo University, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 JAPAN).

I have found no evidence of a significant relationship between the phenomena you talk about. Perhaps you should read my last book, "Introduction to Geomagnetic Fields" (Cambridge University Press, 1997) which discusses the realistic relationships of the solar activity to processes on Earth. --Wallace H. Campbell,


3. How bright is the aurora and how can I demonstrate it?

Not an easy question to answer. The brightness of the aurora is related to the energy flux carried by particles hitting the atmosphere. That energy flux
is EF=(number of particles/cm2/sec)*(average energy per particle). In the aurora the average energy per particle is about 3000 eV--that is the energy acquired by a charged particle falling through a voltage difference of 3000 V. The number of particles per cm2 per sec hitting the atmosphere is a typical aurora is about 2 billion per cm2 per sec. Cast in electrical terms, this can be described in terms of an electrical current (the 2 billion particles per cm2 per sec is equivalent to a current of about 3.3 microamps per m2 - note change of units from cm to m) and, if each particle--charge carrier--had 3000 eV energy this would be a power flux of 3000*3.3*10-6 Watts/m2 = .0099 Watts per m2.

If you wanted to simulate the aurora you would have to:

1. Build a system that would liberate about 2 billion electrons/cm2/sec from some surface.

2. Accelerate those electrons through a 3000V potential difference (in a vacuum so that the electrons were not hitting air.

3. Pass the accelerated electrons through a thin membrane separating the vacuum from air at low pressure (say about .1 to 1% of atmospheric pressure)

4. When the accelerated electrons hit the air, the air should emit light with many (although not all) the characteristic colors seen in the aurora.

In terms of demonstrating the physics of what goes on, a television set duplicates much of what happens in the aurora: electrons are generated from a hot filament in a TV tube, accelerated through 25000V, and hit a phosphor (rather than air) to create light.


General Space Weather | Effects on Earth | Noaa Space Weather Scales | ACE Real-Time Solar Wind