colorectal. pertaining to or of the nature of the colon and the rectum. colorectal polyp. benign or malignant; most commonly occurs at the anorectal junction in middle-aged dogs, causing diarrhea, dyschezia and rectal bleeding.
Although favorable conditions for tornadoes in the United States can occur at any time, they are most common in spring and least common in winter. Because spring is a transitional period for the climate, there are more chances of cooler air meeting with warmer air, resulting in more thunderstorms.
Tornadoes have been observed on every continent other than Antarctica but there are areas which have a higher occurrence than others. The US has the most tornadoes annually, normally between 800-1000 a year; many of these occur in 'Tornado Alley', this area includes the states of Oklahoma, Texas, Kansas, Nebraska. tornado is defined as a 'violently rotating column of air which is in contact with the ground' (NWS). The word tornado is derived from the Spanish word tornar (to turn) and the Spanish word tronada (thunderstorm).