[War Thunder Crack
Saija Grzegorek
Thunder is the sound caused by lightning.[1][2][3] Depending upon the distance from and nature of the lightning, it can range from a long, low rumble to a sudden, loud crack. The sudden increase in temperature and hence pressure caused by the lightning produces rapid expansion of the air in the path of a lightning bolt.[4] In turn, this expansion of air creates a sonic shock wave, often referred to as a "thunderclap" or "peal of thunder". The scientific study of thunder is known as brontology and the irrational fear (phobia) of thunder is called brontophobia.
The cause of thunder has been the subject of centuries of speculation and scientific inquiry.[7] Early thinking was that it was made by deities, but the ancient Greek philosophers attributed it to natural causes, such as wind striking clouds (Anaximander, Aristotle) and movement of air within clouds (Democritus).[8] The Roman philosopher Lucretius held it was from the sound of hail colliding within clouds.[8] By the mid-19th century, the accepted theory was that lightning produced a vacuum and that the collapse of that vacuum produced what is known as thunder.[7]
Scientists have agreed since the 20th century that thunder must begin with a shock wave in the air due to the sudden thermal expansion of the plasma in the lightning channel.[9][8] The temperature inside the lightning channel, measured by spectral analysis, varies during its 50 μs existence, rising sharply from an initial temperature of about 20,000 K to about 30,000 K, then dropping away gradually to about 10,000 K. The average is about 20,400 K (20,100 C; 36,300 F).[10] This heating causes a rapid outward expansion, impacting the surrounding cooler air at a speed faster than sound would otherwise travel. The resultant outward-moving pulse is a shock wave,[11] similar in principle to the shock wave formed by an explosion, or at the front of a supersonic aircraft. Near the source, the sound pressure level of thunder is usually 165 to 180 dB, but can exceed 200 dB in some cases.[12]
Experimental studies of simulated lightning have produced results largely consistent with this model, though there is continued debate about the precise physical mechanisms of the process.[13][9] Other causes have also been proposed, relying on electrodynamic effects of the enormous current acting on the plasma in the bolt of lightning.[14]
The shock wave in thunder is sufficient to cause property damage[7] and injury, such as internal contusion, to individuals nearby[15] Thunder can rupture the eardrums of people nearby, leading to permanently impaired hearing.[7] Even if not, it can lead to temporary deafness.[7]
Vavrek et al. (n.d.) reported that the sounds of thunder fall into categories based on loudness, duration, and pitch.[7] Claps are loud sounds lasting 0.2 to 2 seconds and containing higher pitches. Peals are sounds changing in loudness and pitch. Rolls are irregular mixtures of loudness and pitches. Rumbles are less loud, last for longer (up to more than 30 seconds), and are of low pitch.[16]
Inversion thunder results when lightning strikes between cloud and ground occur during a temperature inversion; the resulting thunder sounds have significantly greater acoustic energy than from the same distance in a non-inversion condition. In an inversion, the air near the ground is cooler than the higher air; inversions often occur when warm moist air passes above a cold front. Within a temperature inversion, the sound energy is prevented from dispersing vertically as it would in a non-inversion and is thus concentrated in the near-ground layer.[17]
This translates to approximately 3 s/km (4.8 s/mi); saying "one thousand and one... one thousand and two..." is a useful method of counting the seconds from the perception of a given lightning flash to the perception of its thunder (which can be used to gauge the proximity of lightning for the sake of safety). Thus, take the counted seconds and divide by five, this will produce the distance in miles from the lightning strike.[20]
Close-in lightning has been described first as a clicking or cloth-tearing sound, then a cannon shot sound or loud crack/snap, followed by continuous rumbling.[7] The early sounds are from the leader parts of lightning, then the near parts of the return stroke, then the distant parts of the return stroke.[7]
**LAWN & GARDEN: High density rate improves fill and establishment while reducing weed opportunity **OPEN SPACE: Economical rangeland density for larger acreage but requires longer establishment period
With rain came green grass and life. These grasses that evolved in the harshest of climate will surely thrive where people live now. Begin to heal the land and the future climate by planting this shortgrass kit. When established, this grass is a native survivor even if the thunder doesn't produce rain.
In the heat of summer Thunder Turf may go dormant, but upon each subsequent rainfall it greens right up. Self-seeding native perennials. Location pictured left is in extremely thin soil on top of a rocky plateau in the western Hill Country. Average rainfall belt of 17-19 inches. Really cold mornings - no problem! Ranges all the way to Sonora desert, 110 degree temps common for places like Phoenix and Tucson - no problem!
In the spirit of military service, Arctic Thunder Open House is an event hosted by Joint Base Elmendorf-Richardson to give back to the local community. We open our doors every other year and share our unique life and culture with a community who contributes so much to our ability to engage globally and protect locally.
In previous years, this event has seen attendance upwards of 250,000 people. We will have dozens of static displays spanning 30 acres, containing inventory from around the Department of Defense and the Department of Homeland Security. We also anticipate international partners participating in some capacity. You can expect multiple military aerial demonstrations, civilian aerial demonstrations, and of course our joint-force demonstration.
General questions? Please contact Joint Base Elmendorf-Richardson and 673d Air Base Wing Public Affairs (907) 552-8151, Option 3, or via email at arctic....@us.af.mil with the subject heading "2024 ATOH."
MEDIA: All media representatives interested in covering the 2024 ATOH should contact JBER and 673d ABW Public Affairs at (907) 551-8995 or via email at jber.pa....@us.af.mil with the subject heading " Media at 2024 ATOH." All media requesting credentialing must read the ATOH Media Ground Rules and complete/email the ATOH Media Visit Request to the above address.
First aid will be provided to address dehydration, treatment for minor cuts and bruises, and the application of emergency medications (ex. Epi-pens). Medical personnel will stabilize patients and coordinate transportation to a higher level of care for all other injuries/illnesses
In the event of rain, some flying demonstrations may be delayed; however, unless the weather poses a serious threat to the safety of the visitors and participants, the show will proceed as scheduled with some modifications.
At this time, the U.S. Air Force Thunderbirds and the U.S. Army Golden Knights are confirmed as the headliners for both days.
The F-22 Demonstration Team, the PACAF C-17 Demonstration Team, and others will also perform, as well as the Joint Forces Demonstration from JBER.
There will be several aerial performances, so a small camera and/or video camera wouldn't be a bad idea. While there are no restrictions on taking photos or videotaping the show, large camera bags are not permitted. Leave unnecessary camera accessories at home or put them in a small bag.
For those with babies and young children, strollers, small diaper bags with snacks and baby bottles, and over-the-ear protection are encouraged. Keep in mind all strollers and bags will be searched before entering the flight line gates.
For those arriving from north of Joint Base Elmendorf-Richardson (Eagle River or the Valley), please enter through the Fort Richardson Gate via D Street Exit.
For those arriving from Anchorage or south of Joint Base Elmendorf-Richardson, please enter through the Boniface Gate via Boniface Parkway.
Go-carts
Wagons
Umbrellas
All pets are prohibited from the Arctic Thunder grounds. Service animals assisting physically challenged guests will be authorized. At no time will pets be left unattended outside the area or in vehicles.
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International Council of Air Shows
Arctic Thunder Open House
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