why would jet planes leave trails of white streaks when they are high in the atmosphere?
438824
Where jets fly the atmosphere is very cold and the water vapor from the jets exhaust condenses and freezes into ice crystals.  THat is why you see the contrail, 0r condensation trail.
178830
Windshear is usually caused by topography, the lay of the land.  For example, large drop-offs at the end of a runway, and are noted in pilot briefings.  One can carry extra speed or altitude on landing to get through these spots.  Microbursts are far more dangerous, since they occur as a function of weather, usually thunderstorms, and can be anywhere.  The most dangerous time for aircraft is when they are low and slow, that is close to the ground as when landing, and operating slightly above stall speed, again as when landing.  Power is what the pilot needs to get through these microbursts, and that is where jet-powered aircraft have a problem.  When a jet engine has been throttled down, necessary for landing, simply shoving the throttles forward does not mean immediate power available.  The engines need a few seconds to regain rotational speed, to "spool up", as we pilots say, before major power is available.  Those few seconds are what can spell the difference between a safe landing or go-around, and a smoking wreck.  Some of the major airports are installing doppler sensors which can usually detect these microbursts, but they are still deadly.
349893
So you can tell how tall they are, and so they're more visible from higher altitudes.  No joke, each section of 20 feet (in America at least) is red or white, and that way they don't blend into the sky the way steel blends into the clouds.
147667
As far as the commercial airjets are concerned they do not carry radar.  The air traffic controllers track the aircraft on radar and ensure that planes are flying far enough behind the plane in front, and are not in the path of another plane.\n\nThe lights are on planes so that you can tell which direction the planes are traveling.  One side is red the other is green, depending on which light is on your left side, you can tell if the plane is flying to you or away from you.  The tail light also helps.  It will not allow you to avoid collisions, just to give you an idea of the direction planes around you are flying.\n\nAnd believe me, once you get above the cloud deck and flying at night, those lights can be seen for miles.  It's actually worse flying during the day, because you can't see the planes as well.\n\nIf you are travelling by plane (private) past a certain distance you have to file a flight plan, so that the air traffic controllers know your coming and can keep track of you during your flight, and keep all other flights away from you.\n\nAir collisions are actually very rare.  Lights do not prevent air collisions, air traffic controllers do.  They have a high stress job, but it's a very important job.
1124040
The 'diamonds' present in afterburner exhaust from a jet engine are standing shock waves from interaction with the nozzle and the atmosphere as the exhaust gases exit the engine at supersonic speeds.  There is some correlation between the numbers of diamonds seen in the exhaust and the speed of the exhaust gases themselves, but not necessarily the speed of the craft using the engine.  Also they are not absolute, in that each single diamond does not represent a 1 Mach speed gradient.
294528
A cirrus cloud is a type of cloud comprised of ice crystals and characterized by thin, wisplike strands, often accompanied by tufts. Sometimes these wispy clouds are so extensive that they are virtually indistinguishable from one another, forming a veil or sheet called "cirrostratus". Sometimes convection at high altitudes produces another form of cirrus called "cirrocumulus" a pattern of small cloud tufts. The name "cirrus" is derived from a Latin word meaning "wisp of hair."\n\nMany cirrus clouds produce hairlike filaments made of snowflakes or heavier ice crystals that precipitate from them. These "fall streaks", a form of virga, often indicate the difference in the motion of air (wind shear) between the upper part of the cirrus cloud and the air below it. Sometimes the top of the cirrus cloud is moving rapidly above a slower layer of air, or the streak is falling into a faster moving lower layer. The directions of these winds can also vary.\n\nCirrus usually form at altitudes above 5000 meters (16,000 feet). The fall streaks may appear straight when wind shear is absent, giving the clouds the appearance of a comma (cirrus uncinus), or tangled, an indication of high-level turbulence. The snowflakes or ice crystals evaporate before reaching the ground.
846386
The answer is Cirrus Clouds.\n\nA cirrus cloud is a type of cloud composed of ice crystals and characterized by thin, wisplike strands, often accompanied by tufts. Sometimes these wispy clouds are so extensive that they are virtually indistinguishable from one another, forming a veil or sheet called "cirrostratus". Sometimes convection at high altitudes produces another form of cirrus called "cirrocumulus" a pattern of small cloud tufts. The name "cirrus" is derived from a Latin word meaning "wisp of hair."\n\nMany cirrus clouds produce hairlike filaments made of the heavier ice crystals that precipitate from them. These "fall streaks", a form of virga, often indicate the difference in the motion of air (wind shear) between the upper part of the cirrus cloud and the air below it. Sometimes the top of the cirrus cloud is moving rapidly above a slower layer of air, or the streak is falling into a faster moving lower layer. The directions of these winds can also vary.\n\nCirrus usually form at altitudes above 5000 meters (16,000 feet). The fall streaks may appear straight when wind shear is absent, giving the clouds the appearance of a comma (cirrus uncinus), or tangled, an indication of high-level turbulence. The falling ice crystals evaporate before reaching the ground.\n\nCirrus clouds contribute both to the atmosphere's greenhouse effect and to the earth's albedo (the amount of sunlight the earth reflects); consequently it has not been determined for certain whether the net effect of cirrus clouds is to warm or cool the earth. Much of the difficulty lies in modelling the albedo effect of clouds composed of various size and shape crystals. Older models tended to underestimate the albedo effect of cirrus. Refinements of these models will improve climate predictions.\n\nIf there are many cirrus clouds in the sky it may be a sign that a frontal system or upper air disturbance is approaching. Cirrus clouds can also be the remnants of a thunderstorm. A large shield of cirrus and cirrostratus typically accompanies the high altitude outflow of hurricanes/typhoons. Cirrus clouds have been observed to develop after the persistent formation of condensation trails from aircraft. The effects of condensation trails on cirrus cloud enhancement is an increasingly prominent part of the discussion about aviation and climate change.\n\nCirrus and Aviation Cirrus (- Smog, see: Contrail) filter the sunlight, thus altering the quality and diminishing the quantity of the Sun's radiation that reaches the surface of Earth.
619362
It is called a contrail,  condensation trail or vapour trail.\n\nCombustion of airplane fuel generates steam in the exhaust. At high altitudes the cold temperature of the atmosphere causes the steam to condense into water droplet or ice crystals (depending on the temperature). \n\nThe condensed water droplets / ice crystals disperse light, making them visible.
407481
According to wikipedia (as far as weather is concerned!):\n"Calm conditions, especially with clear skies, indicate the dominance of a high pressure area. Because highs are regions of descending air, they discourage the formation of phenomena typically associated with weather, such as clouds, wind, and precipitation. Calm conditions, though, may also result from a circumstance known as "the calm before the storm," in which a large thunderstorm cell to the west may be updrafting the westerly wind before it can arrive locally. This situation is readily identifiable by looking to the west — such an approaching storm will be close enough to be unmistakable."\n\nThere you have it! :-)\nhttp://en.wikipedia.org/wiki/Weather_lore
827915
Fairly good, from what I gather.  It doesn't render a plane invisible, but it reduces the radar signature so it's much closer before you see it.  Close enough that you can't do much about it.  They take care of more than bounce off the airframe.  The engines are buried so you can't see reflection off the compressor blades in front, and the exhaust is diffused to reduce the heat signature as well.  Pretty well obscured from all angles.\n\nThis makes them real interesting when you see them go over.  I was out in the yard one night and saw a formation of four lights in a triangle (one was slightly back and to the side of the first light) and caught my breath.  This ENORMOUS triangle was creeping through the sky and the lights were steady white, not flashing red and green like normal planes have.  I assume that was to resemble stars, yet allow the planes to see each other.  There was no noise at all.  I gathered my wits enough to look at the center of the triangle to see stars there.  If I hadn't seen stars, I think I would have gone in my pants.  But I saw stars, so I knew it wasn't a huge solid object.  When they were right on top, there was a soft whooshing/whining sound of the engines, which faded quickly.  There isn't even SOUND to warn you!  If you fly something llike that, you obviously have to keep an eye on radar for other planes in the area, because they sure as hell can't see you.
615749
the shape of the fuselage tends not to reflect a large amount of radar waves.  i think the B-2 has the radar image the same size as that of a bird.\n\nalso, the fuselage is coated with a substance that absorbs radar waves.  so the shape of the fuselage and the texture of the skin of the fuselage work together to lower the amount of radar waves that are reflected off its surface and 'seen' by the enemy.
25218
Stealth jets, especially the F-117 use a special radar anti-reflective coating and sharp angles to deflect radar signals making them hard to detect on radar and you can't find something if you can't detect it, unless you have a ground spotter calling in coordinates but by the time it is called in the jet has already flown over.  The engine on a stealth jet are also designed to minimize heat exhaust and run cooler than your average jet engine, again, making it hard for heat tracking missiles to lock on.  The skin of a stealth jet, namely the F-117 make it very unstable and requires almost complete computer control during flight, though the pilot can make manual course corrections, it's stability during flight is maintained by a computer without the computer the jet would be too unstable for a human to fly.\n\nThey are stealth to some extent and they mostly fly at night, also, rain somewhat dulls the effects of the special coating and sharp angles of the plane so they typically fly at night in either cloudy or clear skies and in those conditions, they are very, very hard to find.  A F-117 appears to a radar, if it sees it at all to be a small bird like a seagull.\n\nDon't ask what the coating is made of, it is classified.
588652
They end up becoming the 'seeds' of clouds.  That is, water in the air condenses around them, & once the process starts, those condensation  trails sometimes form into clouds up to 500 miles long.\n\nI read about it in, I believe, Popular Science a couple years ago.  There was also a fascinating article about a study that took place during the 3 days in 9/01 when all planes in the U.S. were grounded:  due apparently to the reduced cloud cover, temps everywhere were a couple degrees higher those days!
208738
The suggestions given ahead of me are a popular but untrue.\n\nLightning rods are sometimes hit by lightning, but their main purpose is to bleed charge from the ground up thru the point of the rod.\n\nClouds have charge from various sources in the cloud. Small pieces of sand blowing together and other various things. All this charge gets stored up in the clouds.\n\nWhen enough charge builds and has nowhere else to go, the path of least resistance to the ground is where the charge dissipates.\n\nThe actual mechanism is complicated, and there are what are called leaders which travel from the ground UP, and this sets off a series of events leading to the actual discharge.\n\nAnyway......the clouds and the ground act like a giant capacitor in essence.\n\nThe points on the lightning rods are areas of extremely high electric fields. The points are placed on them on purpose and for this reason. This ensures that charge will bleed off AT the points of the rods. The charges that bleed off then end up mixing with the excess and opposite charges in the clouds in the vicinity. This helps reduce the electric field, which is responsible for causing lightning in the first place.\n\nIf this field can be reduced then the chance for a discharge is also reduced and the structure will (hopefully) be safe from lightning damage.\n\nAll the buildings around the universities here have multiple small spikes on them every few feet, for just this purpose.\n\nTake a look at an airplane wing next time you get a chance. You will see small spikes at the tips, or you will see what looks like a rod with bristles at the end. This is a series of 'points' from which charge from the 'skin' of the plane will be bled of during flight and reduce the chance for interference with communications and other instrumentation on the plane.
567444
Because it's invisible air has to do something to get noticed.  Hence, air weather events.
972802
They fly because of Bernoulli's theroem, which states that a moving gas has a lower pressure than a stationary one.  The wing has a curve across the top, and a flat underside.  That means that air going over the top has to move faster than the air going under the wing, which creates a lower pressure area on top of the wing.  The higher air pressure under the wing pushes up on the wing.\n\nYou can experience something similar by putting your finger over the jet in a jacuzzi.  If you hold it close to the opening, the fast moving water flowing around your finger will have a lower pressure than the surrounding water, and you will feel a slight pull on your finger towards the jet.  Move your finger back a little, and you will feel the weight of the water hitting your finger and pushing it away.\n\nAs far as balancing the plane, the fuel is moved around just like transparentearth said, and the manufacturer of the plane has carefully calculated where the center of gravity of the plane is, and the pilots have detailed information about how the load the plane is carrying should be distributed.
776377
Contrails are condensation trails (sometimes vapour trails): artificial cirrus clouds made by the exhaust of aircraft engines or wingtip vortices which precipitate a stream of tiny ice crystals in moist, frigid upper air. Contrary to appearances, they are not air pollution as such, though might be considered visual pollution.