Understanding space weather

Coronal Holes

The sun is continually releasing hot gases from its surface, a steady stream of particles. this is made up of protons and electrons. The solar wind flows out from the sun towards earth. the magnetic field lines on the sun's surface hold in this solar wind most of the time, but sometimes these magnetic lines get stretched and release the solar wind from the sun and they head towards earth. this is called a Solar wind stream. A solar wind stream from a coronal hole is normally faster than normal. For example, the solar wind usually leaves the sun at speeds of around 250 miles (400 kilometers) per second, but solar wind leaving through the center of a coronal hole travels much faster, up to 500 miles (800 kilometers) per second. When these solar wind particles reach the earth, which takes two to four days, depending on their speed, modest geomagnetic storms can result. High-speed wind gusts can also disturb satellites in earth orbit.

Solar flares

Solar flares are short-term outbursts on the sun, caused by the sudden release of energy stored in twisted magnetic fields in the solar atmosphere.

Corona mass ejections

A coronal mass ejection, or CME, for short, is an ejection of large amounts of matter from the sun’s atmosphere, or corona. One of the most spectacular displays of solar activity, CMEs can fling into space billions of tons of solar material, called plasma.

The Magnetosphere

You probably already know that the earth has a magnetic field. You may not realize this field stretches way out into space—at least 37,000 miles (60,000 kilometers)—to form a protective bubble known as the magnetosphere.

The magnetosphere is important because it shields us from interplanetary space weather. Charged particles cannot easily cross the lines of a magnetic field. The result is that most of the particles in the incoming solar wind are deflected around the earth by the earth’s magnetic field.

However, charged particles are not the only component of the solar wind. The solar wind also carries with it interplanetary magnetic field, or IMF, which is a magnetic field from the sun. The IMF can influence solar weather by disrupting the earth’s magnetosphere. How?

The earth’s magnetic field and the IMF connect at the polar caps, and it’s here that energy and particles can and do enter the magnetosphere. If the incoming IMF points south, its interconnection with the earth’s magnetic field becomes especially strong. The effect is like widening a hole—suddenly more energy and particles enter the magnetosphere. Auroras intensify, and geomagnetic storms become likely. For this reason, scientists pay careful attention to not only the strength but also the orientation of incoming magnetic fields from the sun. South-pointing magnetic fields can spell trouble, while north-pointing fields usually coincide with calmer conditions.

Forecasting

The BZ term is used as a measurement of how north or south the IMF goes. if the BZ is north there is less chance of seeing the aurora. if it tilts south then your in for an amazing view. this fluxuates from time to time so its the most important thing to keep an eye on.

also another measurement used of how visable the Aurora is from your location (lattitude) is KP numbers. there numbered 1 to 9. if the aurora reaches kp5 then the measurement of storm levels come in. which kp5 is known as a G1 minor storm, kp6 is known as G2 moderate storm, kp7 is G3 kp8 is G4 and so on.

also keep any on the speed and density of the solar wind, the faster the particels the more stretched the magnetosphere gets pushing the BZ south. so its another good source of information. I do most of my forecasting of the spaceweather site

http://www.spaceweatherlive.com/

they give you updates on how storm conditions are playing out. using dials and bar charts.

another good link to use is the aurora oval. this is an animated model that shows the visable aurora and its updated every 15 mins, so its a great tool to use for that realtime info.