High Alps

Exploration of the High Alps began in the 18th century, with Horace-Bénédict de Saussure.

The occurrence of favorable meteorological conditions during several successive seasons can increase the extent of the snowfields and lower the limit of seemingly permanent snow, while the opposite may cause the limit to rise higher on the flanks of the mountains.

In some parts of the Alps the limit is about 2,400 m elevation, while in others it cannot be placed much below 2,900 m. As very little snow remains on rocks angled more than 60°, this is soon removed by the wind, some steep masses of rock remain bare even near the summits of the highest peaks, but as almost every spot offering the least hold for vegetation is covered with snow, few flowering plants are seen above 3,350 m. The climate of the glacial region has often been compared to that of the polar regions, but they are very different.

Here, intense solar radiation by day, which raises the surface when dry to a temperature approaching 27°C, alternates with severe frost by night.

There, the Sun, which never sets is only able to send feeble rays that maintain a low temperature, rarely rising more than a few degrees above the freezing point.