Another phenomenon that that has only occurred a few times in middle earth history is the tornado that has struck Shire abut luckily did not cause much damage. Tornados are violent air masses that extend off thunderstorms and touch down to the ground. Tornados occur when large cool polar air masses meet warm tropical air masses. When the tornado touches down, winds of up to 300 miles per hour can occur. The reason the damage was minimal was because houses in Shire are built under ground and in hills so the Hobbits were safe from flying debris and the intense wind.
Often times these immense storms cause extreme lightning which is a result of opposite charged particles attracting and form a "stepped ladder" and as soon as there is a conductive path (when the particles are ground) the negative charged particles run down the ladder and cause a visible strike of lightning.
Image sources:
http://blog.weflyspitfires.com/wp-content/uploads/2010/10/storm.jpg
http://stalinsmoustache.files.wordpress.com/2010/01/shire02.jpg
http://img233.imageshack.us/i/middleearthmapwallpaper.jpg/sr=1
