Thunderstorms, with their jagged bursts of lightning and roaring thunder, are actually one of nature’s primary
mechanisms for transferring heat from the surface of the earth into the atmosphere. A thunderstorm starts when low-lying pockets of warm air from the surface of the earth begin to rise. The pockets of warm air float upward through the air above that is both cooler and heavier. The rising pockets cool as their pressure decreases, and their latent heat is released above the condensation line through the formation of cumulus clouds.
What will happen with these clouds depends on the temperature of the atmosphere. In winter, the air temperature differential between higher and lower altitudes is not extremely great, and the temperature of the rising air mass drops more slowly. During these colder months, the atmosphere, therefore, tends to remain rather stable. In summer, however, when there is a high accumulation of heat near the earth’s surface, in direct contrast to the considerably colder air higher up, the temperature differential between higher and lower altitudes is much more pronounced. As warm air rises in this type of environment, the temperature drops much more rapidly than it does in winter; when the temperature drops more than 4 degrees Fahrenheit per thousand feet of altitude, cumulus clouds aggregate into a single massive cumulonimbus cloud, or thunderhead.
In isolation, a single thunderstorm is an impressive but fairly benign way for Mother Earth to defuse trapped heat from her surface; thunderstorms, however, can appear in concert, and the resulting show, while extremely impressive, can also prove extraordinarily destructive. When there is a large-scale collision between cold air and warm air masses during the summer months, a squall line, or series of thunderheads, may develop. It is common for a squall line to begin when an advancing cold front meets up with and forces itself under a layer of warm and moist air, creating a line of thunderstorms that races forward at speeds of approximately forty miles per hour. A squall line, which can be hundreds of miles long and can contain fifty distinct thunderheads, is a magnificent force of nature with incredible potential for destruction. Within the squall line, often near its southern end, can be found supercells, long-lived rotating storms of exceptional strength that serve as the source of tornadoes.

There is nothing to suggest that Evelyn Glennie is profoundly deaf. She insists that her deafness is irrelevant to her musicianship, but there is no doubt that her obvious handicap has turned a remarkable career into a miraculous one. Glennie was eight when her hearing began to fail; by twelve she had lost it completely and feared she would have to give up the music she loved. But a doctor’s suggestion that she should become an accountant rather than follow a hopeless musical career strengthened her will to succeed.
As it turned out, music was one of the most advantageous careers she could have chosen and is one reason why her speech remains so extraordinarily correct, despite her deafness. Occasionally she listens to recordings by holding a cassette player between her knees, interpreting the vibrations and the shaking movements. Her deafness is one of the reasons for her unique style, for she cannot listen and be influenced by other performances and she has often declared that getting her hearing back would be the worst thing that could happen to her.
As a result of her devotion to her music and her determination to succeed, she has doubled the range of works available for percussion music in Europe and introduced instruments previously unheard of in the west. She has also asked composers to write more than fifty new pieces of music for these instruments, and has set up a library of three hundred works for other musicians to use.
(Adapted from Richmond FCE Practice Tests)

Earthquakes are amongst the most destructive natural disasters. They usually strike without any warning and result in a great loss of life and an enormous demolition of buildings. Additionally, they may cause devastating landslides or create gigantic tidal waves (44) ______, in fact, are colossal walls of water smashing into seashores with such force that they are (45) ______ of destroying coastal cities. (46) ______, the vast majority of fatalities and serious injuries come about when buildings collapse.
Most frequently, the earthquake lasts 30 to 60 seconds, so usually there is no time to (47) ______ the mortal upshot once the shaking starts. The savage forces of an earthquake trigger off a complex chain reaction in the building's structure when it is shaken, lifted, pushed or pulled. A building's height, its shape and (48) ______ factors such as construction materials are the most significant factors deciding about the survival or collapse of the structure and, consequently, about the life or death of its inhabitants.