The telephone number for the British Dental Health Foundation's Word of Mouth dental phobia helpline has changed to 0870 333 1188. While as many as four out of five Americans admit being afraid of the dentist, it is estimated that one in seven Americans never get any dental treatment at all because of dental phobia.
The troposphere is the lowermost portion of Earth's atmosphere and the one in which most weather phenomena occur; this layer extends to an altitude of 7-17 km, depending on latitude. Generally, jets fly near the top of this layer. The troposphere is directly below the stratosphere. The word troposphere stems from the Greek tropos for turning or mixing. This region, constantly in motion, is the densest layer. Nitrogen and oxygen are the primary gases, within this region. The tropopause marks the limit of the troposphere and the beginning of the stratosphere. The temperature above the tropopause increases slowly with height up to about 50 km. In telecommunication, the term troposphere has the following meanings: 1. The lower layers of atmosphere, in which the change of temperature with height is relatively large.
stratosphere (strÄtÂ´ÉsfÄr) , second lowest layer of the earth's atmosphere. The level from which it extends outward varies with latitude; it begins c.51/2 mi (9 km) above the poles, c.6 or 7 mi (c.10 or 11 km) in the middle latitudes, and c.10 mi (16 km) at the equator, and extends outward c.20 mi (32 km).tratosphere The layer of the earth's atmosphere that lies above the troposphere and extends to about 50 km above the earth's surface. The temperature within the stratosphere remains fairly constant but can rise in the upper regions of this layer due to absorption of ultraviolet radiation by ozone. See ozone layer.