Firehouse Friday Chat – with Jack & Mack

Jack & Mack

Jack & Mack NOV 13th 2020

Meet Jack a 30 year veteran with a mustache, like an eyebrow dropping down for a drink. His first wife said he was like mascara – runs at the first sign of emotion. He has a deep, throaty, genuine laugh, like the sound a dog makes just before it throws up.

Meet Mack, his first wife said he was like a photocopier – just useful for reproduction! His second wife said he was like a lava lamp- fun to look at but not practical. Jack says, he’s like a laxative because he irritates the crap out of you!

Jack: “ I heard there was some trouble at your base the other night? A Colonel comes up to the guard post and asks if anything happened during the last shift
“Nothing much sir” says the private soldier on duty “just the spade handle got broken” “And what were you doing with the spade that it broke, private?”
“Just burying the guard dog, sir”
“What happened to the guard dog, private?”
“It was run over by the firetruck.”
“What bloody firetruck?”
“The one putting out the fire in the armory, sir.”
Colonel, now as red as a firetruck, visibly shaking in anger, shouts: “There was a F***in’ fire in the F***in armory? Why the F***in’ hell are you only telling me now?”
“Well had I told you straight away you would just get a heart attack like the Major did, sir.”

Mack: Waaah! Hey Jack, seriously, do you know why your firetrucks are red?

Jack: “Well, because firetrucks have six wheels, six is half a dozen. Usually when someone is using half a dozen and a dozen, they are referring to eggs. Eggs come from chickens, a male chicken is a rooster, roosters are often on steeples, steeples are are tall, like a mast on a ship, ships go on the sea, in the sea there are fish and fish have fins and the Fins fought the Russians and the Russian flag is red…….plus its easy to see at night! In the early 20th century, Ford only offered vehicles in black so a fire truck in red would stand out!

Mack:” Actually it’s not the best color at night. Standing out from the crowd is obviously a good quality for a fire truck — or any emergency vehicle — to have. Rather than red, studies have shown that yellow or lime green is most easily seen after dark.

Jack: “Today, red remains by far the most popular color for fire trucks and a variety of other emergency vehicles. However, yes, you will also see many other colors of fire trucks. It’s not uncommon to see fire trucks that are white, yellow, blue, orange, green, and even black around the world!

Jimmy S and Frank W, from EUCOM ask Mack: “Can you help with a presentation on blast effects of nuclear weapons for recruits?”

Mack: “Let’s start with the term “ground zero.” This refers to the point on the earth’s surface immediately below (or above) the point of detonation. For a burst over (or under) water, the corresponding point is generally called “surface zero”. The term “surface zero” or “surface ground zero” is also commonly used for ground surface and underground explosions. Sometimes you may see publications refer to zero as the “hypocenter” of the explosion.

Let’s next look at blast effect. Most damage comes from the explosive blast. The shock wave of air radiates outward, producing sudden changes in air pressure that can crush objects, and high winds that can knock objects down. In general, large buildings are destroyed by the change in air pressure, while people and objects such as trees and utility poles are destroyed by the wind.

The magnitude of the blast effect is related to the height of the burst above ground level. For any given distance from the center of the explosion, there is an optimum burst height that will produce the greatest change in air pressure, called overpressure, and the greater the distance the greater the optimum burst height. As a result, a burst on the surface produces the greatest overpressure at very close ranges, but less overpressure than an air burst at somewhat longer ranges.

When a nuclear weapon is detonated on or near Earth’s surface, the blast digs out a large crater. Some of the material that used in be in the crater is deposited on the rim of the crater; the rest is carried up into the air and returns to Earth as radioactive fallout. An explosion that is farther above the Earth’s surface than the radius of the fireball does not dig a crater and produces negligible immediate fallout. For the most part, a nuclear blast kills people by indirect means rather than by direct pressure.

Next let’s discuss thermal radiation. Approximately 35 percent of the energy from a nuclear explosion is an intense burst of thermal radiation, i.e., heat. The effects are similar to the effect of a two-second flash from an enormous sunlamp. Since the thermal radiation travels at roughly the speed of light, the flash of light and heat precedes the blast wave by several seconds, just as lightning is seen before thunder is heard.

The visible light will produce “flash-blindness” in people who are looking in the direction of the explosion. Flash-blindness can last for several minutes, after which recovery is total. If the flash is focused through the lens of the eye, a permanent retinal burn will result. At Hiroshima and Nagasaki, there were many cases of flash-blindness, but only one case of retinal burn, among the survivors. On the other hand, anyone flash-blinded while driving a car could easily cause permanent injury to himself and to others.

Skin burns result from higher intensities of light, and therefore take place closer to the point of explosion. First-degree, second-degree and third-degree burns can occur at distances of five miles away from the blast or more. Third-degree burns over 24 percent of the body, or second-degree burns over 30 percent of the body, will result in serious shock, and will probably prove fatal unless prompt, specialized medical care is available. The entire United States has facilities to treat 1,000 or 2,000 severe burn cases. A single nuclear weapon could produce more than 10,000.

The thermal radiation from a nuclear explosion can directly ignite kindling materials. In general, ignitable materials outside the house, such as leaves or newspapers, are not surrounded by enough combustible material to generate a self-sustaining fire. Fires more likely to spread are those caused by thermal radiation passing through windows to ignite beds and overstuffed furniture inside houses. Another possible source of fires, which might be more damaging in urban areas, is indirect. Blast damage to Stores, water heaters, furnaces, electrical circuits or gas lines would ignite fires where fuel is plentiful.

Direct nuclear radiation occurs at the time of the explosion. It can be very intense, but its range is limited. For large nuclear weapons, the range of intense direct radiation is less than the range of lethal blast and thermal radiation effects. However, in the case of smaller weapons, direct radiation may be the lethal effect with the greatest range. Direct radiation did substantial damage to the residents of Hiroshima and Nagasaki. Human response to ionizing radiation is subject to great scientific uncertainty and intense controversy. It seems likely that even small doses of radiation do some harm.

Fallout radiation is received from particles that are made radioactive by the effects of the explosion, and subsequently distributed at varying distances from the site of the blast. While any nuclear explosion in the atmosphere produces some fallout, the fallout is far greater if the burst is on the surface, or at least low enough for the firebalI to touch the ground. The significant hazards come from particles scooped up from the ground and irradiated by the nuclear explosion. The radioactive particles that rise only a short distance (those in the “stem” of the familiar mushroom cloud) will fall back to earth within a matter of minutes, landing close to the center of the explosion. Such particles are unlikely to cause many deaths, because they will fall in areas where most people have already been killed. However, the radioactivity will complicate efforts at rescue or eventual reconstruction. The radioactive particles that rise higher will be carried some distance by the wind before returning to Earth, and hence the area and intensity of the fallout is strongly influenced by local weather conditions. Much of the material is simply blown downwind in a long plume. Rainfall also can have a significant influence on the ways in which radiation from smaller weapons is deposited, since rain will carry contaminated particles to the ground. The areas receiving such contaminated rainfall would become “hot spots,” with greater radiation intensity than their surroundings.

Finally you will need to explain the types of burst. The destructive force associated with a nuclear explosion vary with the location of the point of burst in relation to the surface of the earth.

The main types are:

– High Altitude Burst

Detonation above 100,000 feet. Destrutive forces do no significantly affect the ground.

– Air Burst

The fireball does not touch the ground. Detonation is below 100,000 feet.

– Surface Burst

Detontation occurs at or slightly above the actual surface of the earth. One of the greatest results of the type of burst is the amount of radioactive debris and fallout, and the force of the blast wave.

– Sub-surface Burst

Detonation occurs under ground or under water. Depth determines destructive forces on the surface.

Jack: “I’ve learned something today Mack – good job Sir!”

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