The ice sheet at the Pole, nearly two miles thick, is constantly shifting, carrying the facility at the Pole along with it at the rate of about 30 ft. a year. Nearly 90 percent of the ice flowing across West Antarctica converges into ice streams that are the most dynamic, and perhaps unstable, components of the ice sheet. Recent glaciological observations have yielded evidence that some of these West Antarctic ice streams may be responding to climatic and sea level changes of the recent past, changes that could lead to more rapid retreat and global sea-level rise in the future. A few active volcanoes may also affect the ice sheet's behavior. The Antarctic climate offers a formidable challenge to those who venture there in quest of scientific knowledge.
Absolute humidity is lower than on the Sahara.
Annual snowfall in much of the interior is less than two inches. Exhibit 4 Antarctic temperatures. Spring and fall, in polar terms, are more aptly morning and evening twilight. Particularly in the continental interior, the temperature drops quickly when the Sun sets in March, and rises with the Sun's rise in September. The data were collected by unattended automatic weather stations and transmitted by satellite every two minutes to the University of Wisconsin in Madison, from where they were sent by request over the Internet to a winterer at McMurdo Station, who produced this graph as part of an evaluation of latitudinal temperature variations.