Please note: We are aware that the data presented here is, on occasion, fluctuating beyond normal limits. This is due to a technical problem that is currently beyond our control.
The Dome A automatic weather station has temperature sensors at different heights, which allows us to measure the microclimate of the region. Above the snow, sensors appear at one metre, two metres and four metres, while below the snow they appear at 0.1 metres, one metre, three metres and 10 metres. The temperature graph shows the reading from the one metre sensor. At 10 metres depth, seasonal temperature variations are damped out. The temperature at this depth is close to the annual average surface temperature.
Wind speeds at Dome A are very low, and during winter exceptionally strong surface inversions develop. It is not unusual for the air temperature one metre above the surface to be 10ºC colder than the temperature two metres above the surface. In the polar regions during winter, inversions are nearly always present because the sun is very low in the sky. The inversion occurs because the snow surface cools down when there is little radiation coming in from the sun, and this cools the air that is in contact with the snow. The low wind speed prevents this cool air from mixing with warmer air above.
Wind data is not collected during winter. This is not because there is no wind at Dome A during winter! It is simply too cold for the anemometers to work properly during this time of the year.
A wind rose shows how wind speed and direction are distributed at Dome A. It gives a graphical representation of how often winds of particular strengths blow from particular directions.
Relative humidity is the amount of moisture in the air as a percentage of the amount that the air can actually hold. Warmer air can hold more moisture than cooler air, which means that for a given amount of atmospheric moisture, relative humidity will be lower if air is warmer than it would be if the air is cooler.
Air pressure, or atmospheric pressure, is defined as the force being exerted on a point on the earth’s surface by the mass of atmosphere above it.