Solar winds are caused by variance in the magnetic field of the sun. Certain lines in the magnetic field allow particles to travel outward easily and to pick up speed as they move.
The solar winds consist of streams of plasma escaping from the sun's upper atmosphere. They are mainly composed of protons and electrons that have the energy needed to escape the sun's gravity. The open lines of the sun's magnetic field spiral outward in a pinwheel formation, and the movement of particles along these lines can be seen with a sufficiently powerful telescope.
Solar winds vary in overall energy and speed, but they always break the speed of sound. While thermal energy is part of what propels the solar winds, an additional factor allows them to achieve their high speeds. This factor is not yet known to scientists, but it is believed to have something to do with the sun's magnetic field.
Coronal mass ejections are massive releases of solar wind that usually accompany solar flares. The material ejected may contain oxygen, iron or helium. Ejections that travel in the direction of the Earth can potentially cause a geomagnetic storm that disrupts radio transmissions and electrical power lines.