Weather impacts hot air balloon flight throughout the year. Conditions have to be next to perfect in most levels of the troposphere, the area in which weather occurs and hot air balloons fly. The best time of year to fly a hot air balloon is during the summer months. High-pressure dominates most of the United States during this time of year, stabilizing flight conditions. Daytime temperatures also contributes to flight success. Temperatures are coolest in the early morning hours as the sun rises. The cool air near the surface, with light winds, allows the warm air inside the balloon to lift, giving flight to passengers.
Albuquerque International Balloon Fiesta
Albuquerque International Balloon Fiesta happens every October at Balloon Fiesta Park in Albuquerque, New Mexico. Pilots from more than 22 countries have been invited to fly in the popular international event. The 2015 event theme is “Where Dreams Take Flight”. The 44th annual event will features 550 hot air and gas balloons, of which nearly a hundred are highly anticipated special shape balloons.
The five morning mass ascensions, launching both weekends and mid-week, are the most popular events. Other favorite events include the Balloon Glows, Special Shape Rodeo and Music Fiesta. Over 500 hot air balloons launching in various waves in search of the famous Albuquerque Box.
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Albuquerque Box
According to NOAA: A weather phenomenon known as the “Albuquerque Box” produces an atmospheric wind pattern that results in balloons remaining over the park during the morning hours.
The Albuquerque box is essentially a valley wind pattern which develops under certain “stable” conditions. During the nighttime hours, the air near the ground is cooled by the process of radiational cooling. This process is most efficient with clear skies, low humidity and light wind. Cooler, and therefore more dense, air flows downslope and pools at lower elevations such as along arroyos and river valleys – as depicted in by the white arrows in the figure below. The cool air that pools in the Rio Grande valley is shallow (generally no more than a few hundred feet in depth). During the early morning hours this “drainage wind” flows from north to south down the valley from higher to lower elevations much as any fluid flows downhill. In much of the Albuquerque metro area, including the balloon park, a north wind of generally less than 10 mph can result.
The stable “river of air” or drainage wind described above occurs below a temperature inversion which separates it from warmer, less dense air above the inversion, just as vinegar is separated from oil by differences in density. The wind direction in the airmass above the shallow inversion can be different than that below the inversion. In an “ideal” box pattern, the wind blows in exactly the opposite direction, with a north wind at the surface (blue arrow) and a south wind above the surface (red arrow), as shown in the figure to the right. A skillful pilot can bring a balloon back to near the point of takeoff by changing altitudes to ride wind currents in different directions. Upon takeoff the pilot first heads south toward downtown, then ascends higher where the winds will take the balloon back north toward the balloon fiesta grounds.
For WeatherNation: Joshua Cozart
(Headline image & Video: Albuquerque International Balloon Fiesta)