Prabhupada: But actually is there any bird called thunderbird?
Jagadisa: It’s a legendary bird from Indian legend. American Indian.
Prabhupada: Indian legend?
Brahmananda: Of the American Indians, the red Indians. Sometimes their chiefs are called Chief Thunderbird. It’s a popular name for their chiefs.
Prabhupada: Oh. Oh. We have got an idea of thunderbird. The bird flies in the, near the cloud in expectation of water, and they are not afraid of thunder. That is called cataka. That example is given by Rupa Gosvami. The cataka does not take water from ground. They will take water when it falls from the cloud. So in the beginning of every cloud there is thunder. So this bird, because they expecting water from the cloud, the cloud is giving him thunder, but still he does not, will not take water from ground.
Dhira Krsna: In what connection do the Gosvamis use that example to illustrate?
Prabhupada: Example means a devotee will take mercy from Krsna, not from the material world. Even there is thunder, Krsna does not give mercy but puts him into difficulty, still, he will not take any mercy from the material world.
Morning Walk — July 6, 1975, Chicago
Source for the following JULY 9, 2008:
Sometimes thunder claps, sometimes it rumbles. Claps tend to be 0.2- to 2-second-long cracks that accompany close lightning. Lightning that occurs farther away tends to produce rumbles, rather than claps. This is because higher frequencies tend to be more rapidly absorbed by the surrounding environment, while the lower frequency waves sometimes travel distances of 10 to 15 miles (even 25 miles under the right conditions). These long-distance travelers can come from different parts of the lightning bolt, bounce against terrain and buildings, or be refracted by temperature variations in the atmosphere, resulting in a myriad of sound waves reaching an observer’s ears at different times. When this happens from repeated lightning bolts from one storm, and other storms chime in, you can wind up with rumbling, or rolling, thunder.
Regardless of whether lightning is positive or negative, thunder is produced the same way. Thunder is the acoustic shock wave resulting from the extreme heat generated by a lightning flash. Lightning can be as hot as 54,000°F, a temperature that is five times the surface of the sun! When lightning occurs, it heats the air surrounding its channel to that same incredible temperature in a fraction of a second.
Like all gases, when air molecules are heated, they expand. The faster they are heated, the faster their rate of expansion. But when air is heated to 54,000°F in a fraction of a second, a phenomenon known as “explosive expansion” occurs. This is where air expands so rapidly that it compresses the air in front of it, forming a shock wave similar to a sonic boon addition, the temperature of the atmosphere affects the thunder sound you hear as well as how far away you can hear it. Sound waves move faster in warm air than they do in cool air. Typically, the air temperature decreases with height. When this occurs, thunder will normally have an audible range up to 10 miles.
However, when the air temperature increases with height, called an inversion, sound waves are refracted (bent back toward the earth) as they move due to their faster motion in the warmer air. Normally, only the direct sound of thunder is heard. But refraction can add some additional sound, effectively amplifying the thunder and making it sound louder. This is more common in the winter as thunderstorms develop in the warm air above a cooler surface air mass. If the lightning in these “elevated thunderstorms” remains above the inversion, then most of the thunder sound also remains above the inversion. However, much of the sound waves from cloud-to-ground strikes remain below the inversion giving thunder a much louder impact.
