why do flights do not produce sound at night,and why do they produce sound at day time?
87332
Because you are sleeping and can't hear them.\n\nSame as a tree falling in the woods.  If you are not there, it didn't make a sound, right?\n\nObviously, the lower the altitude, the more likely you will hear the jet engines.  At night, maybe you are seeing planes flying at 30,000 ft, and thus , not hearing them, or what you hear might blend in with ambient noise in the evening.  But I doubt there is a difference in actual sound perception of the same plane at a given altitude during night or day.
700445
It heats up the atmosphere in the day time and at night when there is no sun, heat rises from the ground creating disturbances in the atmoshpere, aka wind. The same applies to cold air sinking from the upper layers of the atmosphere to the ground.
8404
Noone can hear the sound of rushing quanta.....\n\nI'm sure at the molecular level their is sound.....but it is far below our abilities to hear unaided\n\n\nBTW DSJ.....the sun doesn't circle the earth,the earth orbits the sun.....
512696
My guess is you are talking about being able to see the flashing lights of a plane at night but cant hear it. Or seeing a high plane with contrails during the day but cant hear that either. Light travels 186,282 mps while sound is only 1100 feet per second. So you see something your mind knows is making noise, but cant hear it because of the distance. Now if the sound has not dispersed through the air by the time it gets to you, then you hear it, but since you cant see what is making it, you dont realize it.
289119
All communication channels have some noise in them, and it generally does not cause any problems if the communication signal is strong enough to override the noise. However, if the signal gets weak enough, then the noise causes the "hissing" sound you hear on a quiet AM radio band channel (which is hard to find because of all the interference from distant stations). Tune to the very top or bottom of the AM  dial to hear the channel hissing noise better. With modern digital communications like HDTV, channel noise causes errors in some of the binary digits being transmitted called "bit errors". If there are enough bit errors occurring in the channel due to the channel noise, then you can actually see some of the blotches on your TV screen where the pixels have gotten corrupted by the channel noise. On cable TV signals that have been transmitted over satellite channels, you see this also sometimes even if your TV is not an HDTV television set.
362504
Sound is a waveform passing through a medium (in this case air). Cooler night air is denser than warm daytime air and therefore easier to travel through and propagate. Other factors already mentioned contribute to it seeming louder, but do not help it to travel further.
287266
my husband also works at night,he is always tired too.but may i suggest as i have to him,blacking the windows..fooling you that it is night,also run a fan,the sound should help you feel refreshed when you wake and,it also drowns out unwanted daytime sounds.this is the only way i could sleep when i worked night shift,hope you sleep well..ZZZZZz
444478
Chew some gum that helps with your ears because with out it your ears may pop; yawning at take-off and landing helps too. I pass the time with a good book or my portable DVD player....then your mind isn't on the flight it's on the movie. If you don't have on you can get one at Wal-mart for like a hundred bucks. You can even take a CD player and listen to your favorite music...just relax plane rides are no biggie!
844883
Actually it is not true in most part of the world. Only the industrialised nations have put a ban or restriction on the niose level coming from an aeroplane and especially at night.\n\nI live just a couple of kilometers from the modern airport with landing strip almost in sight and 'planes keep landing all the time. There is no difference in their noise between the day time or the night time. So I guess you do not hear any noise because you are asleep.\n\nMoreover, the aerport you are talking about may actually have a ban or time restriction on night time landing or take off.
74
There make very low frequency sounds that we cannot hear. They also make sounds that we do hear and it is because they what other animals to hear it.
283342
Although we can't hear the sound the sun makes in a usual way from earth -- since sound can't travel through the vacuum of space -- we can make measurements of how portions of the sun are rising and falling and deduce what vibrations must be going through the sun because of this.  These vibrations are equivalent to sound, though at a much lower frequency.  For instance, middle C on a musical instrument vibrates the air back and forth 256 times a second.  For one vibration on the sun to go back and forth typically takes 5 minutes.\n\nSo the vibrations are at a frequency far below what human hearing could pick up, but if you multiply the frequencies to bring them into the range of what we can hear, the site below lets us listen to what the sun would then sound like.  Click on the "Hear the Sun Sing" link when you get there.
885483
I love this question! I have two things. First the supers in my building yell back and forth to eachother day and night (they are 2 brothers and one sister and old). So some nights they will be in he hallway outside my apartment or outside my window outside the building yelling back and forth. Maybe they have hearing problems. The second thing is a car alarm. There is this one SUV that someone owns in my building. If the wind blows the freakin alarm goes off. My apt is ground floor, facing the street so its like its going off in my room. ggrrrrr
282325
Medium wave and short wave radio signals act differently during daytime and nighttime. During the day, AM signals travel by groundwave, refracting around the curve of the earth over a distance up to a few hundred miles (or kilometers) from the signal transmitter. However, after sunset, changes in the ionosphere cause AM signals to travel by skywave, enabling AM radio stations to be heard much farther from their point of origin than is normal during the day. This phenomenon can be easily observed by scanning an AM radio dial at night. As a result, many broadcast stations are required as a condition of license to reduce their broadcasting power significantly after sunset, or even to suspend broadcasting entirely during nighttime hours. (Such stations are commonly referred to as daytimers.)\n\nSome other radio stations are granted clear channel rights, meaning that they broadcast on frequencies whose use is restricted and thus relatively unaffected by interference from other stations.
1185144
Radio signals, both AM and FM typically carry farther at night due to temperature layering of the atmosphere, which causes the radio waves heading to outer space reflect back down to earth. It's an atmospheric skip effect.
442307
I'm quoting myself, for this question has been asked before.\n\nBats are not blind. \nWhat about phrasing the question the other way around? Bats don't have to fly at night because they're blind; rather they have evolved to occupy an ecological niche that involves crepuscular-nocturnal activity. Some bats took the evolutionary path towards small size and echolocation; those are the ones with small eyes and large ears. It's a matter of adaptation: they don't use their eyes as much as their sense of hearing, but usually structures or functions are not lost unless the _loss_ implies some benefit. Relatively small eyes are still functioning eyes!\n\nOther bats that are much bigger, have large eyes and good eyesight; the so-called flying foxes.\nAnd to return to the question: a good reason that bats fly during the night is that they encounter less competition from other animals for their food, which may be insects, flowers, fruits, fish, etc.\nCheck the Special Topics at the Animal Diversity Web: \nhttp://animaldiversity.ummz.umich.edu/site/accounts/information/Chiroptera.html
956289
Yeah, it will produce a compression wave in the air - which is the definition of sound.  It doesnt matter if someone is there to hear it or not.  A sound is still made.
654209
Most of the time, clouds have no such effect on planes of any size. \nIt is only storm clouds that shake the plane, and that is because storm clouds have violent winds swirling within them.\nPilots always try to avoid storm clouds. \nBut some storm clouds are so tall and wide that the pilot, to save lots of time and distance, will fly through the edge of the cloud, avoiding the most-violent part.\nMost modern planes, and all jets, have weather radar, which shows the violent part of the cloud.\n\nClouds DO have two minor effects on the flying experience:\n1) entering a cloud, which is denser than plain air, causes the engine noises to sound louder;\n2) when descending into a cloud from clear sunshine, the clouds will suddenly diffuse the sunshine, sending bright light into BOTH sides of the plane. It could be momentarily blinding.