Solar wind

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As many people know my favourite topic is the Solar wind. The solar wind is a constant stream of plasma and charged particles from the upper atmosphere of the Sun, called Corona, spreading into the space. The interplanetary magnetic field is embedded within the solar wind plasma. The solar wind varies in density, speed and temperature over the time and over the solar latitude.



The speed of the solar wind ranges from slow solar wind 300 - 500 km/s to fast solar wind 500 - 1000 km/s and temperature between 10^6 K to 10^5 K. Slow solar wind is almost twice denser than the fast solar wind. The fast solar wind originates from coronal holes, which is the region of open magnetic field lines. The slow solar wind originates from the streamer belts over the closed magnetic field lines.

 The solar minimum, the period of the lowest solar activity, is shown on the left side of the picture. The solar maximum, the period of the highest solar activity, is shown on the right side of the picture. Also the solar wind composition varies according to the solar activity and solar wind features, magnetic clouds and co-rotating interaction regions.  

 Co-rotating interaction regions develops within the solar wind where the fast solar wind literally catches the slow solar wind ahead. The solar wind varies typically between 300 km/s to 800 km/s, depending where the solar wind originates. Fast solar wind comes from the coronal holes and the slow solar wind comes from regions above the helmet streamers. As the Sun rotates it creates the pattern called ballerina skirt. The faster solar wind catches the slower solar wind creating interaction region, where the shock wave may develop.

 Magnetic clouds are features in the solar wind of the solar material ejected into the space. They can be detected by the observation of typical solar wind characteristics and their occurrence rate depends on the solar activity. During solar minimum there is minimum appearance while during solar maximum magnetic clouds are very frequent.  
Location: Helsinki, Finland

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