The Roof of the World is at a height of 8,850 metres, or 29,035 feet. Moreover, it seems to be growing at a rate of 3 cm per year.

On the Tibet side of Everest, part of the landscape rises clearly above the surroundings. This “Tibetan Plateau,” from 100 to 1 000 metres above the surrounding countryside, is one of the largest and highest plateaus in the world. It rises 4 km above sea level and is “drawing nearer to the sky” at an estimated rate of 1cm per year. Chinese scientists think that some parts of the plateau are rising even more quickly–ten times faster than a million years ago, in fact.

An orographic feature as imposing as the Himalayas, or even the Rockies of North America, deflects the winds at different heights in the atmosphere. This has an impact on weather near Nepal, of course, but sometimes all around the world. The winds are forced to follow the mountain’s curvature by rising or sinking; in the case of Mount Everest, they deviate by more than 25,000 feet, to reach the height of the jet stream.

But what is this famous “jet stream”?

It is a region in the atmosphere where the winds reach their peak speeds. This current is usually located in the tropopause, at about 10,000 metres, but a jet stream can form in the lower levels of the atmosphere at night. These b winds generally flow from west to east over the mid-latitudes. To be called a jet stream, the winds must be at least 95km/h, but they can reach as much as 300km/h. The jet stream usually separates cold air in the north from warmer air in the south.Here’s an example from closer to home. When the winter is mild in southern Quebec, it is because the jet stream has shifted toward northern Canada. During a harsh winter, however, it is not unusual for the jet stream to move as far south as the Gulf of Mexico, bringing cold air to the central United States.

Inside the jet stream itself, there are often zones of higher winds. These zones play an important role in forming precipitation and depressions.

A jet stream blowing with the strength of a hurricane blasts the rocky, icy summit of Everest nearly all year long. Observers of the Roof of the World can tell when the jet stream is blowing there, in fact, from the long white stream of ice crystals extending out from the tip of the mountain. Those wishing to actually stand on the summit have to choose their moment carefully: the mountain is most inviting in early May, when the jet stream is pushed northward over Tibet by the arrival of the monsoon.

Bernard and his team have picked the best time to try their luck. So let’s wish them “kind” winds!