****************************************************** CLIMATE, WEATHER & TEMPERATURE ****************************************************** *************************************** CLIMATE *************************************** ********************* COOLING OVER TIME ********************* __________ QUESTION: Was Antarctica always cold? If so how could the dinosaurs or plants live there? Why do the researchers disagree about that? ANSWER from Terry Trimingham on January 12, 1995 I spoke with a couple of geologists here, and they tell me that a long time ago the Earth had a much warmer climate overall. Between 120 million and 40 million years ago the climate in Antarctica was warm enough to support both dinosaurs and plants. We all know that Antarctica is covered in ice now, but how it came to be that way has not been completed agreed upon. While no one knows for sure, a couple of theories are being tested. One theory says that the ice covering the continent has been around a very long time (from 40 million years ago to the present). The other theory says that the ice has come and gone, come and gone, numerous times in the past history of Antarctica. There is data that supports both theories, so nothing definitive can be concluded at this time. __________ QUESTION: Why was it warm when the dinosaurs roamed and cold now? ANSWER from Katy McNitt on January 26, 1995: There are many reasons, but the main one is that Antarctica hasn't always been at the South Pole. When dinosaurs roamed, Antarctica was farther north, and temperatures were warmer all over the Earth. There are many, many things which affect the planet's temperature, like the sun, and clouds, and ocean and air circulation. __________ QUESTION: During the dinosaur era, the temperature in Antarctica was very warm. How did it change so drastically? How did the scientists figure out that Antarctica used to be so warm? ANSWER from Katy McNitt on January 12, 1995, S-257 "Monitoring Climatic Change," Amundsen-Scott South Pole Station It wasn't just Antarctica that was warmer a hundred million years ago when the dinosaurs were around. The average temperatures of the whole planet were about 10-15 degrees C warmer than they are now. We know this because scientists can study air bubbles trapped in the ice, and the concentrations of different gases in the air bubbles are closely related to temperature. By drilling deep into the polar ice sheets, scientists can study bubbles that have been there for hundreds of thousands of years! Can you imagine how these scientists know how old the bubbles are? Another hard part is figuring out why the Earth--Antarctica in particular--is cooler now. The most well-known explanation is that Antarctica isn't where it used to be, and that it has collected ice since it moved to the South Pole from the lower latitudes which are also associated with geologic change could be massive volcanic activity. What do you suppose might happen to the amount of sunlight and heat that normally reach the Earth if hundreds of volcanoes erupt at the same time? Another possibility is the effect that animals and plants have on the climate by changing the concentrations of certain things in the oceans and the atmosphere. Just as an example, we humans are releasing a lot of "greenhouse gases" into the air, which tend to warm the Earth, but at the same time we're creating a lot of smog-type pollution, which blocks sunlight and tends to cool the Earth. These things aren't equal, though, so we can't just hope they'll cancel each other out; and there are other things to consider, like health! All sorts of other things change, too. The Earth's orbit around the sun changes over thousands of years, and the distance between the Earth and the sun has a direct effect on global temperatures. We're used to the North Pole pointing away from the sun during winter in the northern hemisphere, when the Earth is closest to the sun. But what would happen to our winter if the North Pole faced the sun during winter? This apparently happens every few thousand years. And what about the tilt of the Earth's axis? That changes, too, creating big changes in the seasonal distribution of sunlight. *************************** IMPORTANCE OF CLIMATE *************************** __________ QUESTION: Why would we in North America care about Antarctica's weather patterns? ANSWER from Deane Rink Not everything needs a practical reason; sometimes knowledge can be valuable just for its own sake. But Antarctic weather does affect weather in the mid-latitudes in the following ways. Atmospheric circulation patterns are driven by temperature differentials. If there's warm air around the equator and cooler air around the poles, these air masses will tend to flow towards each other as they try to average each other out. It is this mixing of different air masses that creates storm systems, including the ones that buffet the oceans and our more populated continents. ***************************** EFFECTS OF SUDDEN CHANGE? ***************************** __________ QUESTION: What would the consequence be if Antarctica had a sudden climate change? ANSWER from Terry Trimingham on December 24, 1994 I am assuming by "climatic change" you are referring to a sudden warming of the climate of Antarctica. About 98 percent of the Antarctic Continent is covered by ice, with an average thickness of more than 1.5 kilometers, a maximum thickness of nearly 5 kilometers, and a volume of 25 million cubic kilometers. The ice cover is a result of thousands of years of accumulation of snow, and is so thick that it actually depresses the Earth's crust in certain areas. The depressed crust is lower than sea level in some parts of the continent. The ice cap that covers the continent makes it the worlds loftiest continent, averaging 2500 meters in altitude. Antarctica holds 90 percent of the worlds ice, and 75 percent of its fresh water. If there were a sudden warming to cause this ice to melt completely, it is estimated that the melting combined with the rebound of the ice- depressed crust would cause the worlds sea level to rise about 50 meters. I'll leave you to think about the consequences! ********** PLANTS ********** __________ QUESTION: Did you see plants in Antarctica? ANSWER from Elizabeth Felton on January 24th, 1995: While I was in Antarctica I spent most of my time at the South Pole where there is no life at all except for humans, so I haven't studied any plant life. However, there is some around the coasts of Antarctica. I have read that there are green alga, lichens, and 2 flowering plants. This isn't very much at all. While I was at McMurdo Station, which is on the coast near the Ross Ice Shelf, I saw no plants. Because of the cold, most plants and animals can't survive. I'm sure you know that just about every plant that you have in your backyard dies in the wintertime. Well, in Antarctica it is like an eternal wintertime. So, it takes quite a strong plant to survive the freezing temperatures. **************************************** TEMPERATURE **************************************** ************************************ ARCTIC/ANTARCTIC TEMPERATURES ************************************ __________ QUESTION: Why does it get so much colder in the Antarctic than in the Arctic? ANSWER from Terry Trimingham on December 16, 1994 We are not really sure that it does get THAT much colder in the Antarctic. The lowest temperatures on Earth recorded have been recorded in the Antarctic at Vostock Station, which is located on the Polar Plateau. The Polar Plateau is an accumulation of thousands of years of snowfalls that have piled up on top of each other to make a thick plateau of ice. The U.S. base at the South Pole is also located on the Polar Plateau, and it has a pressure altitude equivalent to 10,800 ft elevation (when the actual elevation is only 9,300 ft). This is probably the main reason temperatures in the Antarctic are lower than those in the Arctic. When you gain elevation, you also drop in temperature. You might try to find out if atmospheric pressure has an effect on temperatures. Also, the Antarctic is a very LARGE mass of ice and ice-covered land, whereas the Arctic is a lot smaller in actual mass, and there is no land under the North Pole. The vast amounts of white ice in the Antarctic reflect the sun's energy back off the surface of the continent creating a negative radiation balance (more solar energy is reflected than absorbed). This makes the Antarctic a natural "refrigerator." (Look up the term "albedo.") The proximity to water will also temper things, and the Arctic is much closer to water than most parts of the Antarctic. We are not sure about how weather is measured and recorded in the Arctic. Here in the Antarctic we record temperatures at the South Pole and from locations on the Polar Plateau. I believe that a combination of all of the above reasons makes it seem that the Antarctic is a colder place. ********************************* HOTTEST AND COLDEST RECORDS ********************************* __________ QUESTION: What is the hottest temperature ever recorded in Antarctica? ANSWER from NSF publication Facts About The United States Antarctic Program Along the Antarctic Peninsula, temperatures as high as 15 deg C (59 deg F) have been recorded. __________ QUESTION: How cold is it right now, and what was the highest and lowest temperatures ever recorded there. ANSWER from Craig Mundell on Dec 21, 1994: The temperature at McMurdo Station today (22 Dec) is a high of +34 F, a low of +23 F, and a minimum wind-chill of +14 F. The temperature at South Pole Station today is -24 F. The recorded extreme temperatures at McMurdo are a low of -58 F and a high of 47 F. The annual mean temperature is 0 F. The recorded extremes at South Pole Station are a low of -117 F and a high of +3.1 F. The annual mean temperature is -56 F. Also, the coldest temperature ever recorded was -128.6 F at Russia's Vostok Station. ******************************** SUMMER WATER TEMPERATURE ******************************** __________ QUESTION: What is the summer water temperature? ANSWER from Katy McNitt on January 26, 1995: The water near McMurdo is about 28 degrees F, which is colder than the freezing point of fresh water! Brrrrrrrrrrrrrrrrr! *********** SUMMER? *********** __________ QUESTION: If it doesn't get over zero in Antarctica why do you call it summer? ANSWER from Craig Mundell The term "summer" isn't dependent on temperature, rather it has to do with the position of the Earth in relation to the sun. Being in the Southern Hemisphere, our summer (when this part of the world is closest to the sun) is during the winter of the Northern Hemisphere. Also, even though it doesn't get above zero in many parts of Antarctica during the summer, there is a great temperature increase over the winter months. For example, at South Pole Station the winter temperatures can get down to -100 F, while they may increase to 0 F during the summer. Also, at McMurdo Station the winter temperatures can get down to -50 or -60, but will increase to the mid 30s in the summer. This is an incredible increase in temperature that is probably greater than most temperature shifts in the States between summer and winter. ********************************** WATER TEMPERATURE IN WINTER? ********************************** __________ QUESTION: How cold is the water in winter? ANSWER from Nicole Wertz on January 16, 1995 The water stays the same temperature of 28 degrees F year round, just below freezing. Since the air temperature in the winter drops anywhere from -50 to -100 degree F, it freezes the top of the water which is why it gets covered in ice. But the water that doesn't freeze under the ice stays that temperature. When the ice breaks up and floats away in the summer, the water also remains 28 degrees F. ***************************************** WEATHER ***************************************** *********** ACID RAIN *********** __________ QUESTION: Are studies being done on acid rain in Antarctica? What is the pH of the snow? ANSWER: From Jack Dibb on February 7,1995 People studying the composition of glacial snow and ice (like our group) have discovered that the acids in acid rain (mainly H2SO4 and HNO3) have caused a large increase in the concentrations of SO4 and NO3 in snow falling in the northern hemisphere during the 20th century. This increase was caused by pollution and is very clear even on the Greenland ice sheet. Similar studies in Antarctica have not yet shown an anthropogenic signal in these acids (though we can measure increases in the concentration of some other pollution tracers like Pb and CO2). However, the snow is definitely acidic; the mean pH in a pit we sampled at South Pole was 5.5. ****************** AREA VARIATIONS ****************** __________ QUESTION: Can Antarctica be cold in one place and warm in another like the United States? ANSWER from Terry Trimingham on December 21, 1994: Yes, it gets warmer in some places of the Antarctic and colder in others, but I am using relative terms. The weather office here at McMurdo tells me that temperatures on the continent will range from +60F (high) to -50F (low) in the summer time, and +29F (high) to -100F (low) in winter. The Antarctic continent spans about 35 degrees of latitude, from 65 to 90 degrees south. Places at 65 degrees latitude tend to be warmer than those at 90 degrees. (Do you know the name of the research station at 90 degrees south latitude?) Areas on the coast are at low elevation and near the ocean making them more temperate. There are other places in the interior of the continent at high elevation (on the polar plateau) and dry, making for colder temperatures. ************ CYCLONES ************ __________ QUESTION: Why are there so many cyclones around Antarctica? ANSWER from Deane Rink on December 17, 1994 Antarctica is the repository of the world's largest collection of freshwater, contained in the permanent ice sheet. The ice sheet influences the air that circulates around it, cooling it. When that air rushes off the Antarctic continent, dry and cold, being drawn to the seashore margins by gravity, it collides with warmer air masses that have driven southwards by the wind circulation patterns. (The Earth's atmospheric circulation patterns are determined by temperature differentials; where it's hot, the wind is attracted to cooler air, and where it's cool, it's attracted to warmer air. This is because any physical system wants to achieve thermal equilibrium -- when you pour cold water in your hot chocolate, the resulting mixture will be warmer than the cold water and colder than the hot chocolate, reflecting an average of the two) This happens with the Earth's atmosphere. The warmer air masses from the equatorial regions flow towards the pole to equalize the atmospheric temperature differential. In simplified form, the place where these two different-temperature air masses collide is the continental margins of Antarctica, and that's why so many storm systems are created there. These storm systems express themselves in cyclonic patterns because of the Earth's rotation, which adds another element of movement to the already-complicated mixing the air is undergoing. If your local library has a copy of the PLANET EARTH PBS series, one of the seven episodes is entitled "The Climate Puzzle." This episode explains these concepts in more detail with a lot of great visual illustrations, including some from the Antarctic. **************** LAKE FREEZING **************** __________ QUESTION: Why don't the lakes freeze solid? ANSWER from Diana W. Freckman on December 13, 1994: Some of the lakes do freeze solid, the very shallow ones, that is. The other lakes have a really thick ice cover on them that in the summer filters light and heat to the bottom of the lakes. Because the ice cover is so thick, there is not much loss of heat in the winter, and so the bottom of the lakes are warmer than the surface. Therefore, there is no freezing at the bottom. ***************** LONGEST STORM ***************** __________ QUESTION: How many hours has the longest snowstorm been? ANSWER from Guy Guthridge on February 1995: In June 1993 McMurdo Station had hurricane-force winds that lasted more than 3 days. Imagine being in Hurricane Andrew for 3 days instead of the few hours that most people experienced! It was the worst storm in the memory of the station. The duration of that wind pales compared to winds that have been recorded by Australian stations on the coast of Antarctica opposite Australia, where, in winter, gusts have exceeded 200 knots and have stayed above 40 knots for a whole month. These storms are more properly called wind storms than snow storms, although plenty of snow drift is in the air during one of these blows. ********************** WEATHER PREDICTING ********************** __________ QUESTION: Is it hard to predict the weather from hour to hour? ANSWER from Katy McNitt on Feb. 6, 1995: At the South Pole it's almost impossible to predict the weather on a day-to-day basis because there isn't much access to data besides what we see out the window. Hour-to-hour prediction is a little easier because there aren't any mountains or cities obscuring our view, and we can watch clouds approaching from miles away. Generally, the weather doesn't move in very quickly here, anyway. But in McMurdo it's a whole different story, and "Herbies" or windstorms can sneak in without any warning. __________ QUESTION: What happens when there is a mistake in predicting the weather. What could the possible problems be? ANSWER from Katy McNitt on December 29, 1994: Here at the South Pole we don't forecast the weather, mostly because there aren't enough data from weather stations or satellites to see "what's coming our way." Also, we don't usually support remote field camps, and the weather tends to move in pretty slowly. McMurdo, however, is a different story. Storms can move in quickly without much warning there. Restricted visibility can cause people to get lost, which is especially dangerous in below-freezing temperatures. Can you think of the problems this might cause for airplanes, boats, and other forms of transportation? People in McMurdo and at the field camps rely on accurate weather prediction to do their work as safely and efficiently as possible. ******* RAIN ******* __________ QUESTION: Does it ever rain? ANSWER from Lt. Stevens (US Navy) on February 8, 1995: In my three years in the McMurdo Station area, I have never seen it rain or heard of it raining. Other, ten-year people say they have also never seen rain. Rarely has freezing rain been seen. Palmer Station, however, on the other side of the continent does get a lot of rain. It is at a higher latitude and therefore has a warmer climate. ******************* THUNDERSTORMS ******************* __________ QUESTION: Is possible to have thunderstorms in Antarctica? ANSWER: On February 3, 1995 Katy McNitt, LTJG, NOAA, answered: It might be possible in the lower latitudes, for instance, along the Palmer Peninsula, but according to the meteorologists in McMurdo it's almost impossible to get thunderstorms here. We just don't get the required warmth or the cloud formations. ************** TORNADOES ************** __________ QUESTION: Have there ever been tornadoes in Antarctica? ANSWER from Terry Trimingham on December 19, 1994 There aren't tornadoes in Antarctica now, and there probably haven't been any since the continent became so cold and icy. A tornado is actually a vortex of rapidly circulating air around a center of low pressure. It is caused by extremely unstable conditions: warm moist air underneath and very cold air above. The warm air tries to rise, and due to a process called "vorticity" will start to rotate. Evaporative cooling occurs when moist air rises and starts to evaporate, consuming energy in the process (which lowers air temperature). This in turn contributes to even more unstable conditions by widening the gap in temperatures between the warm and cold systems involved in creating the tornado. The bigger the temperature difference and the moister the air, the bigger and more powerful a vortex is created. In Antarctica not only is there very little moisture in the air, but temperature gradients do not ever get to the extremes that you need to start the process that creates a tornado. We have had some whirlwind storms called "cold vortexes" (also known as "cold funnels"), but they are not of the same magnitude as the tornadoes one experiences in the United States. **************** WEATHER DATA **************** __________ QUESTION: We are hoping to record/graph weather information for the week January 30- February 3. Can you provide us with the following information for each of these dates: High/low temperatures, wind velocity, wind chill factor in Antarctica. ANSWER from LT "T" Stevens on February 12, 1995: Temps Avg Wind Wind Max Wind Wind high/low Dir/Spd Chill Speed Chill (Celsius) (deg/kts) (Celsius) (kts) (Celsius) 30 Jan: 0.0/-3.0 270/04 -01/-04 13 -11/-15 31 Jan: -3.0/-7.5 100/07 -09/-15 22 -20/-28 01 Feb: -1.8/-5.0 300/07 -08/-11 17 -17/-21 02 Feb: +3.7/-3.8 000/00 +04/-04 11 -04/-15 03 Feb: -1.5/-7.2 120/08 -08/-15 24 -18/-27 To show that there is a significant difference in weather at various points in Antarctica, I've included a weekly summary for McMurdo and South Pole. Weekly summary for the week 29 Jan - 04 Feb: McMURDO STATION (80 ft above sea level): Max Temp: +3.7C on 02 Feb (Record for 02 Feb, broke old record +1.7C set in 1973) Min Temp: -10.4C on 04 Feb Mean Wind: 07 knots from 220 deg (SW) Peak Wind: 37 knots from 320 deg (NW) on 04 Feb Max Sustained Wind: 28 knots from 310 deg (NW) on 04 Feb There was a trace amount of snow on 04 Feb AMUNDSEN-SCOTT SOUTH POLE STATION (9600 ft above sea level): Max Temp: -29.0C on 31 Jan Min Temp: -44.6C on 04 Feb Records for Min Temp set for 29 Jan and 04 Feb 29 Jan: -39.7C broke record of -38.3C set in 1978 04 Feb: -44.6C broke record of -41.1C set in 1959 Mean Wind: 08 knots from 080 deg (ENE) North at South Pole is oriented towards 0 deg meridian Peak Wind: 13 knots from direction 100 (ESE) on 02 Feb Max Sustained Wind: not recorded at South Pole There was no precipitation at South Pole this period Data courtesy of AG2 Angie Garner and AG2 Alan Manuel, NSFA Weather Division and LCDR John "JJ" Joseph, NSFA Meteorology Officer. ************ WHITEOUTS ************ __________ QUESTION: Are there whiteouts? ANSWER from Tom Stevens in February, 1995 Yes, there are many whiteouts. They can be extremely dangerous when flying helicopters like I do. A whiteout is when all horizon definition and surface definition are lost. It is like flying inside a ping- pong ball! ******************** WIND & WIND CHILL ********************* __________ QUESTION: What is the highest mile per hour wind speed in Antarctica? ANSWER from Craig Mundell on December 8, 1995 The highest wind speed recorded in Antarctica was 212 knots on Mt. Washington. As a comparison, McMurdo has an average wind speed of 10 knots; 101 knots is the recorded high gust. Some of the coasts in Antarctica also represent some of the windiest places in the world. For example, in 1912-1913, the Adelie coast had an average wind speed of 40 mph, 64% of the time. __________ QUESTION: How many miles per hour can the wind blow? ANSWER from "Facts About the US Antarctic Program, NSF92-134": Some coasts of Antarctica are the windiest places in the world. Winds on the Adelie Coast in the winter of 1912-1913 averaged 18 meters/second 64 percent of the time, and gusts have been recorded at nearly 90 meters per second. For reference, 1 mile per hour = .447 meters per second. __________ QUESTION: How do the winds from the Arctic influence the wind chill factor? ANSWER from Terry Trimingham on January 10, 1995: Wind chill factor is affected by wind as follows. If there is no wind, your body perceives the temperature as it truly is. When wind blows, the temperature your body perceives is lower than what the actual temperature is. The relationship between wind and perceived temperatures has been formulated mathematically, and I am sure you can find charts telling what the perceived temps are for what wind speeds. When cold fronts come carrying cold air, the temperatures drop due to the cold air that replaces the warmer air, but the wind chill factor is not affected, the same relationship that has been formulated in charts is maintained.