During the night from Oct-30 to Oct-31 the particles of the extremely strong coronal mass ejection of our sun of the day before smashed into the upper layers of our atmosphere with a speed of 1200km/sec, causing auroras visible even from our lattitude in Europe - a very rare event in Austria.
The red glow is generated either by ionized nitrogen in altitudes around 100km or ionized oxygen in altitudes above 300km, while the green glow is caused by ionized oxygen in altitudes between 100-300km.
Fortunately the clouds disappeared just in time for the great midnight show.