Bonnie Rannald's Photo-Explorations in focus with nature. : National weather service

Saturday, October 17, 2009

National Weather Service Weather Balloon

WEATHER BALLOON RELEASE

Weather is one of my favorite subjects, as I have mentioned on previous posts. It defines my style of photography where interesting weather patterns accent the landscape. Furthermore, I rely on accurate forecasts to stay out of danger and be safe on my journeys. On August 14, 2009, I experienced first hand how our weather is observed and predicted. I was invited by Jane Hollingsworth, the Meteorologist in Charge of the National Weather Service in Reno, Nevada to tour the facility.

The highlight of the tour was the weather balloon release that takes place twice a day in the AM and PM hours, every day of the year. Weather balloons are released from around 900 locations worldwide, simultaneously. The time is set to coincide with Greenwich Mean Time or Universal Time, which in Reno would be at 4Am and again at 4PM. This weather balloon was released at 4 PM.

Weather Balloons are made of latex rubber and when filled with hydrogen measure about 6 feet in diameter. Due to the flammability of hydrogen, the weather balloon was filled in a chamber next to the National Weather Service building.

A radiosonde, or instrument package, hangs below the balloon. It is equipped with battery-powered sensors to record measurements of pressure, temperature, relative humidity, wind speed and direction aloft.

Before the balloon is released into the atmosphere, a call must be made to the local airport control tower, requesting permission so that it will not interfere with any approaching aircraft.

The balloon is then taken out to an open area and released where it will ascend at approximately 1,000 feet per minute. The sensors in the radiosonde are linked to a battery powered radio transmitter that sends measurements to a sensitive ground-tracking antenna. The radio signals are converted to meteorological values and then transmitted to the NOAA National Climatic Data Center.

A weather balloon may rise to over 100,000 feet in the atmosphere and drift more than 180 miles. The journey can last for over two hours where it reaches temperatures as low as –130F and air pressure that is a few thousandths of our surface level. If it enters a strong jet stream, it may travel at speeds in excess of 250 mph. As the balloon rises, it also expands. When the diameter reaches over 20 feet, it will burst. An orange parachute attached to the end of the balloon helps to slow the fall and allows the radiosonde to get safely back to Earth. Each radiosonde comes with a mailing bag and directions on how it should be returned when found. When the radiosonde is returned, it will be repaired and reused, which assists our National Weather Service do their job more efficiently.

Weather balloons play a vital role in providing the data for accurate up-dated forecasts and storm predictions that we rely on for work and play. Thanks to our meteorologists from the National Weather Service, who are ever vigilant, and work 365 days a year, around the clock.

For more information visit these links:

http://www.wrh.noaa.gov/rev/

http://www.wrh.noaa.gov/mso/educate/balloon.html

http://www.srh.noaa.gov/tae/tour-ua.php

What an exciting and interesting photo-adventure this day has been. I love it when I am drawn to an area and not knowing what to expect I get treated to new experiences.

Photography places me in the moment where I can share that moment in time. It becomes a life story as represented by my interaction with the scene. The happiness and beauty or the sorrow and strife; how I focus leaves a lasting impression that might touch the viewer on a spiritual level.

"Reflecting Nature's Artistry"

Many of these images are available on my website:

http://www.bonnierannald.com/

For custom matted and framed images:
Off The Wall

No images on this blog are within Public Domain or are available for free download.

All rights reserved, world-wide and images protected by Digital Millennium Copyright Act (DMCA). All photography, graphics, text, design, and content is copyrighted by Bonnie Rannald and should not be copied, down-loaded, transferred and re-created in any way without the express consent, in writing to Bonnie Rannald. For information on Bonnie Rannald licensed, right-managed images, please submit a written request.

Monday, April 13, 2009

NATURE’S LIGHT SHOW

Photographing Lightning

Here in the Southwest, on warm sunny afternoons when the humidity starts to rise, there is a possibility that thunder cells will develop over the mountains. As evening descends, if the lightning remains localized, I will be in for a special treat: to photograph one of my favorite scenes. I have always been fascinated by thunderstorms. Throughout my childhood in the southern U.S., I was mesmerized by the brilliant flashes of light and the loud cracking thunder, which was followed by a hard downpour of rain. These days, if conditions are right, I will pack up my camera gear and head outdoors in search of lightning photos.

Of all the scenes that I love to photograph, a lightning storm is potentially the most dangerous. To be as safe as possible, I will wait for lightning to form on the horizon, at least twenty miles away. Lightning can strike within a ten-mile range and a bolt can reach for five to ten miles.

I have been most successful with my lightning photos after nightfall, because with a dark sky, I can leave my shutter open and get several strikes on a frame without over exposing. As night approaches if there is lightning over the mountains, I drive out in the desert to get a closer view. After a level location away from trees is found, I set up my camera equipment close to the car. A car will provide shelter and protection during a thunderstorm; however contact must be avoided with the metal sides.

One disadvantage of night photography during stormy weather is that it’s hard to see the movement of the clouds. Because of this, I am always aware of the wind’s speed and direction. If the wind speed increases and I can feel it blowing on my face, it means the storm is headed in my direction, and I had better seek cover. I would rather not be caught outside, standing behind a large metal tripod and getting zapped by billions of volts of static electricity.

All of my lightning photos were taken with my Nikon film cameras before I made the transition to digital. Since these photos were taken at night, I used a cable release to hold the shutter open on the “bulb” setting. The camera was wrapped in a plastic bag to keep it dry, and then secured to a sturdy Bogan tripod. Most of the time, I used a Nikon 80-200mm 2.8 lens with the aperture set at f5.6 and focused on the distant mountains. I will position myself to frame the mountains in the foreground with the lightning striking over them. From trial and error, I can leave the shutter open and get numerous lightning strikes with out overexposing the frame.

The diameter of a typical lightning bolt isn’t much larger than an inch. The reason it appears so much wider is because the light is so bright. The heat produced by a bolt of lightning can get hotter than the surface of the sun, and can raise the air temperature to 50,000 degrees Fahrenheit.

A lightning flash is usually not a single event. It can have up to 42 strokes, occurring at 0.02-second intervals between strokes, followed by a leader stroke. Lightning can and often does strike in the same place twice.

The length of a lightning bolt can be between 2 to 3 miles long, lasts 1/4th second, and carries a current of 1000 Amps at 100 million Volts.

In pursuit of my photography, I strive to be as responsible as possible and take all safety precautions. Since the weather plays a significant role in my landscape photography, I always study the weather forecasts before venturing out on a photo shoot. On several occasions, after I wandered a long distance from my vehicle, I began to notice the fair weather cumulus clouds changing into cumulonimbus or thunderclouds. A couple of times the thunder was very loud and seemed to be almost overhead, so I quickly turned around, picked up my pace and did a fast trot back to my car.

As a rule, thunder can only be heard from a distance of twelve miles. For an estimate on how close the lightning may be, count the seconds between when it flashes and when it thunders. When there is less than 30 seconds, the thunderstorm is within six miles, which puts you in the danger zone. If you are out in the open and cannot find shelter, protect yourself by moving to the lowest elevation. Make yourself as low to the ground as possible by getting in the lightning crouch: with feet held together, squat down; tuck your head to your chest or between your knees; hold your arms tight against your body and place your hands against your ears. This position can offer some protection by allowing the lightning a pathway to flow over your body instead of through your vital organs. Always, if possible, wait for at least 30 minutes after you hear the last clap of thunder before leaving a shelter.

For additional information, please visit
NOAA’S National Weather Service Lightning Safety Web site.