The balloons, which start out measuring about 6 ft. wide before release, expand as they rise to about 20 ft. in diameter! An instrument called a radiosonde is attached to the balloon to measure pressure, temperature and relative humidity as it ascends up into the atmosphere.
These instruments will often endure temperatures as cold as -139 °F (-95 °C), relative humidifies from 0% to 100%, air pressures only a few thousandths of what is found on the Earth's surface, ice, rain, thunderstorms, and wind speeds of almost 200 mph! A transmitter on the radiosonde sends the data back to tracking equipment on the ground every one to two seconds.
Every 12 hours, hundreds of people in places around the world release huge, white balloons into the sky. In addition to the hundreds of balloons launched every 12 hours, weather balloons are used in many research projects to examine aspects of the atmosphere that are difficult to access.
For example, using weather balloons a French meteorologist named Leon Tasman DE Born was able to find the top of the troposphere and the stratosphere beyond. In two hours, a weather balloon can rise above the clouds, higher than the paths of jet planes, passing through the ozone layer in the stratosphere.
$\begingroup$An ordinary weather balloon cannot maneuver horizontally (unless an external force is applied to it) because it lacks the means to do that. It has only one purpose, to soar up to the altitude where the air pressure inside is more than outside and then burst.
At least for a small balloon that's only 1 or 2 hundred feet up you could let it rise up like a kite and tie it off over your desired area. And you'll have the desirable ability to pull it back down to retrieve camera easily.
$\begingroup$A weather balloon is almost constantly moving horizontally. You cannot control this horizontal motion and the balloon is at the mercy of the wind.
A weather balloon is also not designed to hover, but to rise until it bursts somewhere around 100,000 ft. At an isolated weather station in the central United States, a technician emerges from a small brick shed grasping a balloon.
It's not just any birthday party balloon, mind you, but a massive, white sphere more than 5 feet (1.5 meters) in diameter. In the other hand, the scientist grasps a radiosonde, a lightweight cardboard box filled with scientific instruments that's tied to the bottom of the balloon.
As the balloon hurtles away from the Earth, the radiosonde is already hard at work, beaming atmospheric information back to data centers. It may have started out modestly, but now, at almost 18 miles (29 kilometers) high, the balloon has swelled to the size of a moving truck.
Stretched to its limit, the balloon's thin synthetic rubber bursts and sends the tiny radiosonde plummeting back toward Earth. Within seconds, the wind catches a small, orange parachute and slows the device's descent.
Hours later -- and hundreds of miles from where it first lifted off -- the weather balloon touches the ground. More than 70 years after scientists sent up the first experimental weather balloon, they remain the workhorses of modern meteorological forecasts.
Whether it's a tornado warning or the weather report on the 6 o'clock news, weather balloons are what keep people on the ground tuned in to the meteorological workings of the upper atmosphere. Tagging along for the ride was John Jeffries, an American physician known for dabbling in weather observation.
In the skies above Northern Europe, Jeffries hoped to record some first-ever measurements of the upper atmosphere. When the balloon came dangerously close to crashing into the English Channel, however, Jeffries was forced to toss his equipment overboard to lighten the load.
It may be sunny and quiet at sea level, but at 18,000 feet (5,486 meters), a weak storm system could soon turn into something more dangerous. By sending up regular squadrons of balloons to measure the conditions of the upper atmosphere, meteorologists can keep tabs on brewing storms.
With such a limited data set, the best meteorologists can do is predict the weather a few hours into the future. High-altitude weather data is critical for predicting oncoming natural disasters like tornadoes, thunderstorms or flash floods.
Thanks to weather balloons, officials can scramble supplies and emergency personnel to an affected area hours before a weather disaster strikes. In 2009, Massachusetts Institute of Technology scientists Oliver Yes and Justin Lee used a weather balloon, a cooler, a cell phone and a digital camera to take a high altitude photograph of the Earth for less than $150.
Of course, Yes and Lee warn that launching things into the stratosphere can be dangerous . If it's not equipped with proper parachutes, an amateur weather balloon can become a deadly projectile if it falls in an urban area.
The balloons could also provoke a disaster by getting sucked into the jet engines of a passing airliner. During a meteor shower, a high-altitude balloon can collect cosmic dust emitted by the passing space rocks.
Occasionally, an American homeowner wakes up to find a spent weather balloon in his or her backyard. It's a strange sight: tattered strips of neoprene, tangled cords, a crumpled parachute and a small cardboard box.
The core component of the whole assembly is the radiosonde, a shoebox-sized cardboard box packed with three basic atmospheric instruments: The slide is coated with film of lithium chloride (ICL), the electrical resistance of which changes based on the surrounding humidity.
As the air pressure around it decreases at higher altitudes, the canister expands, triggering a sensor. The radiosonde also has a low-powered radio transmitter to relay data from all three instruments back to receivers on the ground.
Holding the whole assembly aloft is a large balloon made of neoprene, a synthetic rubber. The balloons are filled either with helium or hydrogen depending on the preferences of the individual launch station.
However, hydrogen is also very flammable -- a fact that has prompted many explosion-shy weather stations to adopt helium instead. Altogether, a complete weather balloon assembly costs about a few hundred dollars.
The relative cheapness of weather balloons is what has kept them the go-to device for recording weather data for more than six decades. In an isolated field in the middle of Australia, NASA officials slowly inflated a massive helium balloon that would carry a $2 million gamma ray telescope into the upper atmosphere.
Crew members ran for their lives as the telescope smashed into a nearby SUV and ripped through a fence before crumpling into a heap more than 492 feet (150 meters) away. Of the many things that can go wrong during a balloon launch, leaving a trail of destruction is obviously one of the worst.
In the United States, weather stations will typically have an onsite shed built especially for the purpose of balloon inflation. As it fills, he tests the radiosonde's battery, tunes the radio equipment and attaches the whole assembly together with a length of nylon cord.
Once the balloon has inflated to about the size of a yoga ball, the technician ties it off and ushers it outside. Walking the balloon a short distance clear of trees, power lines and other obstacles, he'll simply give it a gentle push upward.
As soon as the balloon begins to float, the radiosonde gets to work, beaming data to weather computers on the ground. By noting the sideways movement of the ascending balloon, they can calculate wind speed and direction at different altitudes.
With less air pressure to rein it in, the gas inside the balloon expands as its altitude rises. The balloon can only expand so much, however, and it will typically burst at altitudes above 15 miles (24.1 kilometers) -- about three times higher than Mount Everest.
If the radiosonde was simply allowed to plummet to earth, it could wreak deadly havoc on human settlements below. As the balloon ascends, the parachute remains folded by the downward rush of air.
When the assembly starts to descend, however, the parachute is blown open, slowing the balloon to a manageable 22 miles per hour (9.8 meters per second). If balloons catch a particularly strong gust of wind, they can travel several hundred miles -- touching down anywhere from a marshy bog to the snowy peaks of the Rocky Mountains.
Sending helicopters to pick up almost 200 weather balloons launched in the United States each day simply isn't in the budget.