The Worst Weather, the Best Place
by Laurie Ann Toupin
As she carefully climbs the icy metal ladder of the weather tower atop Mt. Washington in Sargent's Purchase, NH, 190-kph (120-mph) winds whip around her. The air temperature rises to a balmy minus 15 degrees C (5 degrees F), but the wind-chill makes it feel like 36 degrees C (33 degrees F) below zero.
When she reaches the last step, Nicole ducks her head to shield it from the wind. She grabs onto thick steel cables, and fights the wind as she crawls onto the platform. She is surrounded by a barren, white landscape of drifting snow and raw, rime ice. These cables are the only barrier between her and the rocky ledge below.
Once she feels steady, Plette turns and “sits” in the wind. The gusts that would have blown her over the side just a moment ago now hold her in place while she clears the ice and snow from the wind vane and pitot anemometer. Once free, these instruments will tell her the exact wind direction and wind speed.
“That is my favorite part of my job,” the twenty-five-year-old says with a smile when she gets safely back inside and starts to shed layers of winter gear.
Every other Wednesday, staff meteorologist Plette and a crew of three to nine observers, interns, researchers, and volunteers ascend the mountain in a Bombardier snow tractor. In summer, the drive takes only 25 minutes, but in winter—with drifting snow up to 9 meters (30 feet) deep and average winds of 130 kph (80 mph), it could take as long as six hours.
For the next eight days, the Mt. Washington Observatory will be Plette's home. As one of two staff meteorologists (who alternate eight-day shifts) at the weather station, she will observe weather conditions every hour.
Her shift runs from 4:30 a.m. until 4:30 p.m. At exactly a quarter before the hour, Plette climbs outside the observatory to record dew point temperature, temperature, wind speed, wind direction, cloud height and type, visibility, and type of precipitation.
First, she dons her bib overalls, coat, glove liners, overmitts, boots and overboots, facemask, goggles, and hat. The only part of Plette's skin exposed to the elements is the underside of her nose—so that she can breathe. “When we go outside, we have to be completely covered from head to toe, because with the wind-chill factor, frostbite can occur in minutes,” she says.
If the mountaintop isn't in the fog, which it is almost 60 percent of the time, Plette uses a sling psychrometer to measure the dew point. This instrument has two identical thermometers, except that one is a wet bulb thermometer and one is dry. The wet one has a little piece of cloth that has been soaked in water and taped to the bulb. “We swing the wet thermometer psychrometer around until all the water evaporates off the bulb,” Plette says. She knows when the moisture is gone by keeping track of the temperature. The temperature will continue to drop as long as there is water, because as the water evaporates, it takes heat away from the bulb. (Energy is lost to the phase change of water to water vapor in the form of heat.) Once the temperature begins to go back up, Plette knows all the water has evaporated. “At that point, we measure both temperatures and can calculate the dew point and the relative humidity in the air using a psychrometric calculator that looks like a circular slide rule.”
Relative humidity tells the meteorologists how much water is in the air compared to how much it can hold. Cold air can hold a lot less water than warm air, which is why it feels so dry in the winter.
Every three hours, Plette adds atmospheric pressure to her list of observations. Weather stations worldwide report pressure to determine current weather patterns such as high/low pressure system movements. This helps meteorologists forecast sunshine or rain.
Every six hours, she goes into the thermo-shack, a small, white, wooden box on a pole, to read the maximum and minimum thermometers. The minimum one is an alcohol thermometer. When the temperature decreases, it pushes a small plastic marker to the exact temperature. When the temperature increases, the marker stays put. The maximum thermometer contains mercury, which expands with temperature. If the temperature decreases, the mercury stays at the highest point. After taking a reading, Plette tilts both thermometers to reset them. The lowest temperature ever recorded was minus 44 degrees C (minus 47 degrees F)!
After Plette finishes each observation, she sends this information to the National Weather Service, where meteorologists use the data to compute national weather patterns.
Why Mt. Washington?
The Mt. Washington Observatory traces its roots to a scientific expedition in 1870–71. The station was the first high-elevation, severe-weather station of its kind in the world to take continuous observations. This effort was short-lived, however, as difficult winter conditions caused the observatory to be shut down.
Four scientists tried again in 1932—this time, chaining all the buildings to the ground. Since then, observers there have continuously monitored weather conditions and conducted landmark research in snow and ice physics and the constitution of clouds.
Meteorologists love to study winter weather on the top of Mt. Washington. This winter wasteland sits at a mere 1,886 meters (6,288 feet) above sea level. This is nothing compared to the 4,200-meter (14,000-foot) mountains of the Rockies, or the 8,700-meter (29,000-foot) Himalayan peaks. But Mt. Washington carries the proud distinction of being home to the “worst weather in the world.”
In 1934, observatory researchers clocked a wind gust at 370 kph (231 mph)—the fastest surface wind ever measured.
“The weather is so bad up here because we lie in the path of three different storm tracks,” says Plette. “Our chance of getting a severe storm is usually three times greater than anywhere else, which probably lies in only one storm path.” Storm tracks are defined by the upper airflow, which usually moves from west to east or up the coast. Mt. Washington's storms blow in from the Ohio River Valley, St. Lawrence Seaway, and coastline.
The winds are so extreme because of the mountain's elevation compared to local topography and its relationship to the atmosphere.
The atmosphere has a cap or lid on it called a tropopause, says Plette. This means the winds are squeezed into a smaller vertical distance to go over Mt. Washington than they are when they blow over the valley. “It is just like putting your finger in front of a garden hose,” she continues. “When the hole that the water has to pass through gets smaller, the water comes out with more force. So the winds speed up when the distance they have to pass through gets smaller.”
High wind speeds and arctic-like conditions make this a perfect place for hearty meteorologists to study winter weather.
Scientists from the University of New Hampshire, for example, wanted to find out what kinds of aerosols were in the air. So, on foggy days, Plette placed icing rods outside in the fog. When it was below freezing, rime ice accumulated on the rods. Both ice and rods were sent to UNH to determine the types of aerosols found in the ice. By analyzing the ice, researchers know what kinds of chemicals are in the air, because they know what kinds of chemicals are bound up in the ice.
Lots of Work
If it sounds like a lot of hard work staying up there, it is. “It takes a lot of physical strength to deice all the instruments and keep all the doors free of snow,” Plette says. “We have to be self-reliant.”
You can never underestimate the power of the wind. One night last December, Plette couldn't feel any wind. So, thinking that it must not be that strong, she moved out of the protection of the tower and stood straight up. “As I turned east to make my observation, the wind picked me up a foot into the air and pushed me about 10 meters [30 feet],” she remembers. “It was really cool and the most exciting thing that has happened to me up here so far, but I will never make that mistake again!”
But she has fun, too. A small, red, plastic slide sits beside the stairs leading outside. “We go deck sliding,” Plette says. “We sit on that little sled and let the wind push us across the observation deck. It is so fun!”
Plette hates to see the winter end. “I love it up here in the winter,” she says, “which is odd for me, because I'm a summer person. I've always loved nice hot, humid, sunny weather. But it is like a different planet here.”
“And I have the best view in the world,” she says, as she scans the peaks on the jagged horizon of New Hampshire's famous White Mountain range. “Beats any view in the city.”
Plette got this unusual position because she loved weather, math, and physics. “I asked myself one day, What am I going to do with all of these? I decided to do a joint major in physics and atmospheric science.” She interned at the observatory at the end of her senior year in college, and she's been here ever since.
In addition to observing the mountain's weather conditions, Plette also gives a daily weekday weather forecast on New Hampshire Public Radio.
You could visit this winter planet and Plette. Groups are welcome to come up for a tour or an overnight stay. If you are interested, call the Mt. Washington Weather Discovery Center at (603) 356-2137. And don't worry if you can't come in the winter. You won't have missed the snow! Even in the middle of July on a good year, visitors start climbing from the base in shorts and T-shirts, and by the time they reach the top, they will have passed many patches of snow and ice where drifts have been so deep, they sometimes never completely melt.
- A gaseous suspension of fine solid or liquid particles.
- dew point:
- The temperature at which air becomes saturated and produces dew (water droplets that form on cool surfaces) usually at night.
- The boundary between the troposphere and the stratosphere (about 8 km in polar regions and about 15 km in tropical regions). The regions above the troposphere have more atmospheric stability than those below. The tropopause marks the vertical limit of most clouds and storms.
- wind-chill factor:
- The temperature of windless air that would have the same effect on exposed skin as a combination of wind speed and air temperature.
- What makes the location of the Mt. Washington Observatory a good location for studying winter weather?
[anno: The observatory sits on top of a mountain. The mountain is located in the pathway of three different storm tracks, so Mt. Washington gets more storms than many other places.]
- Name three different measurements that are taken at the Mt. Washington Observatory.
[anno: Answers will vary but could include dew point temperature, temperature, wind speed, wind direction, cloud height and type, visibility, and type of precipitation.]
- Why do the meteorologists study ice samples gathered at the observatory?
[anno: They study the ice samples to find out what kind of chemicals have been frozen in aerosols that float through the air.]