Last year, we answered a question regarding whether or not the Earth's daily maximum temperature always exceeds 100 degrees F. The answer was that, on occasion, it probably does not. For the Earths lowest temperature, the answer is that on each and every day, the minimum temperature, at some inhabited local, always drops below 0 degrees F. We can give this answer with a high degree of assurance because at the South Pole, on only a handful of occasions since temperatures were first recorded in 1957, has the maximum temperature ever exceeded 0 degrees F!

Not only is the South Pole (Amundsen-Scott Station) at the bottom of the world and a long way from the moderating influences of oceans, but it's sitting on ice thousands of feet of ice. The Amundsen-Scott Station is at an elevation of over 9,000 ft, and at Vostok (about 775 miles away), the elevation is approximately 10,800 feet. The ice is over 2 miles thick at Vostok, and it shouldn't be surprising that the our planet's lowest temperature was observed here, -130 degrees F!! Their average annual temperature is more than 100 degrees F lower than it is at nearly every major city in the contiguous US. One look at last months heating bills convinced many of us that our temperatures must have somehow been as low as Vostok's.

Even when the Sun shines for 24 hours a day, as it does at the South Pole from about September 22 to March 22 , the sunshine is not very effective in raising the temperature. This is because Antarctica is an excellent refrigerator, and also, much of the incoming solar energy is reflected back to space. In addition to being the coldest continent, it's the driest and windiest land mass as well. Antarctica is like a pump, forcing both cold air and moisture northward, and it's what primarily drives both the atmospheric and oceanic circulation in the Southern Hemisphere.

Ok, so we've established that the Earth's minimum temperature is below 0 degrees F every day of the year, but is this still the case if we don't include Antarctica? At this time of year, in the far north, the temperatures are often below zero for days at a time. The Sun is still just an infrequent visitor above the Arctic Circle, and despite the fact that there's no land mass at the North Pole, temperatures can approach those observed at the South Pole during the austral winter. For example, on January 16, the minimum official temperature in the world was - 72 degrees F at Oymyakon, Russia (northeastern Siberia), perhaps the coldest inhabited settlement in the Northern Hemisphere. It's reported that in one village in central Siberia, the temperature plummeted to - 94 degrees F!! The all-time coldest temperature in the Northern Hemisphere is -96 degrees F in Verkhoyansk, Siberia. By the way, this is the actual temperature, not wind chill. It's a bit more pleasant today (February 14). In Verkhoyansk, the current temperature is a heartwarming - 57 F. At the South Pole, the current temperature is - 47 F.

While it's always cold in Siberia during the winter, this year, the weather has been bone-chilling and mind-numbing cold. Since early December, the minimum temperature has been below - 60 F or colder somewhere in Siberia almost every single day. The only times when the temperatures didn't fall that far below 0 degrees F was when strong winds and or cloudy skies disrupted the nocturnal radiative heat loss regime. This is the coldest winter in Siberia in at least the past 70 years. The icy grip has been unrelenting, but in Siberia, life goes on. For instance, even though the extreme cold and not exactly modern heating systems have meant that people had to sometimes wear their winter gear inside their homes, in early January, about 200 runners participated in a marathon in the city of Omsk. It would seem to me that after running a few miles and exposing your poor lungs to air below zero, life might not go on very long. Anyway, in the Northern Hemisphere, the minimum temperature in Siberia, and in other northern realms, easily surpasses the 0 degree F mark every day from November through April.

However, once the snow melts, and before it begins to accumulate, temperatures are unlikely to dip much below 0. By late April, the Sun is above the horizon for most of the day in the Arctic, but the land is still mostly snow covered in eastern Siberia, northern Alaska, northern Canada, and northern Scandinavia. Minimum temperatures still will drop below 0 degrees F in May but generally only if skies are clear, allowing heat to be radiated away from the surface and into space. By June, most of the Northern Hemisphere's seasonal snow has melted and with sunlight bathing the surface all day, while the minimum temperatures may not be toasty, they're almost always above zero. Even the air above the huge Greenland Ice Sheet has warmed up enough so that minimum temperatures don't often fall below zero.

Of course, in June, it's winter in the Southern Hemisphere. However, most of the land masses in the Southern Hemisphere lie too close to the equator and too far from the pole to experience subzero temperatures on even the coldest winter day. The Earth is about 3% further from the Sun in June than in December, but since there's so much more water in the Southern Hemisphere, things don't usually cool as quickly and to the same degree as in the Northern Hemisphere. With the exception of Antarctica, and a few small islands, the southern-most areas of Australia, Africa and South America are some distance from the Antarctic Circle (66 1/2 degrees south). But even though there's about 2,000 miles of open water between the tip of South America and Antarctica (not including the Antarctic Peninsula), cold air from the bottom of the world can be pushed northward all the way to southern Brazil. In fact, snow and freezing temperatures affected the coffee crops last July.

Nevertheless, only the Tierra Del Fuego area at the extreme south of Argentina and Chile (55 degrees south latitude) and the Patagonia region of Argentina are near enough to Antarctica to be routinely subjected to icy blasts. While temperatures there dip below zero on many winter days, it's not a "given" as it is in the Arctic. As mentioned above, in the Northern Hemisphere, temperatures are almost always above 0 degrees F during the summer (June - September). So then, excluding the research stations in Antarctica, it would seem that the Earth's minimum daily temperature (for inhabited locations), will not always dip to 0 degrees F.

For more about Siberia's cold temperatures see the Earth Science Picture of the Day for January 11, 2001.