question: Why do sneezes come out clean but forcefully blowing your nose produces snot?
comment: Because it is happening at such high speeds. It essentially vaporizes when it comes out of your nose so it doesn’t seem like an equivalent to the snot you blow your nose into. Also when you are blowing your nose it’s generally because your nose is full, while sneezing happens as a reflex. Fun anecdote from me, I sneeze out of my mouth so very little snot comes out as well.
passages: The function of sneezing is to expel mucus containing foreign particles or irritants and cleanse the nasal cavity. During a sneeze, the soft palate and palatine uvula depress while the back of the tongue elevates to partially close the passage to the mouth so that air ejected from the lungs may be expelled through the nose. Because the closing of the mouth is partial, a considerable amount of this air is usually also expelled from the mouth. The force and extent of the expulsion of the air through the nose varies.
   The tissue is held gently against the nose. Prior to nose blowing, a deep inhale through the mouth provides the air required to eject the nasal mucus. Exhaling hard through both nostrils at once will effectively eject the mucus. The process may need to be repeated several times to sufficiently clear the entire nose.
  
  Section::::Health effects.
   While nose-blowing helps to alleviate symptoms of the common cold and hayfever, the blowing of a nose, when it is done excessively or incorrectly, may bring potential health effects. Nose-blowing generates high pressure in the nostrils. When this pressure is added to a dry nose, it could rupture blood vessels inside the nose, resulting in a nosebleed.
   In a 2000 study, doctors squirted dense liquid dye, which could be seen on x-rays, into the noses of several adult volunteers. The volunteers were induced to sneeze, cough, and blow their noses. It was found that the typical pressure of nose-blowing was 1.3 pounds per square inch, ten times greater than that generated by sneezing or coughing. CT scans showed that nose blowing sent much of the dye into the paranasal sinuses rather than expelling it out the nose. The doctors suspected that nose-blowing may increase the risk of sinus infections by sending bacteria-filled mucus into the sinuses.
   Nose-blowing
  
  Nose-blowing is the act of expelling nasal mucus by exhaling forcefully through the nose. This is usually done into a facial tissue or handkerchief, facial tissues being more hygienic as they are disposed of after each use.
  
  Nose-blowing may be used to alleviate nasal congestion or rhinorrhea (runny nose) resulting from colds or seasonal allergies.
  
  Section::::Technique.
   Examples of preventive techniques are: the deep exhalation of the air in the lungs that would otherwise be used in the act of sneezing, holding the breath in while counting to ten or gently pinching the bridge of the nose for several seconds.
   In extremely rare but documented cases, nose-blowing has resulted in unusual conditions, such as in the case of a woman who fractured her left eye socket after blowing her nose.
  
  Section::::Etiquette.
   The main function of the nose is respiration, and the nasal mucosa lining the nasal cavity and the paranasal sinuses carries out the necessary conditioning of inhaled air by warming and moistening it. Nasal conchae, shell-like bones in the walls of the cavities, play a major part in this process. Filtering of the air by nasal hair in the nostrils prevents large particles from entering the lungs. Sneezing is a reflex to expel unwanted particles from the nose that irritate the mucosal lining. Sneezing can transmit infections, because aerosols are created in which the droplets can harbour pathogens.
   The pressure difference causes the mucosal lining of the sinuses to become swollen and submucosal bleeding follows with further difficulties ventilating the sinus, especially if the orifices are involved. Ultimately fluid or blood will fill the space.
   It is possible that the nasal cycle may exacerbate the nasal congestion caused by the common cold, as the lack of motility of the cilia in one half of the nose may lead to an uncomfortable sensation of not being able to shift mucus by blowing the nose.
  
  Section::::Benefits in breathing.
   Section::::Routes of Administration.:Nasal.
   There can also be behavioural signs; in order to relieve the irritation or flow of mucus, people may wipe or rub their nose with the palm of their hand in an upward motion: an action known as the "nasal salute" or the "allergic salute". This may result in a crease running across the nose (or above each nostril if only one side of the nose is wiped at a time), commonly referred to as the "transverse nasal crease", and can lead to permanent physical deformity if repeated enough.
   Sniffle
  
  A sniffle is the reflex action of inhaling quickly to prevent mucus from flowing from one's nose, as an alternative to blowing the nose. 
  
  Section::::Physiology.
  
  For a fraction of a second, the performer inhales strongly, pulling mucus from the outer part of the nasal cavity higher up, even into the sinus. This action is generally repeated every few seconds or minutes.
  
  Sniffling and runny nose need not come associated with sneezing or coughing. 
   In people who are experiencing seizures, nose wiping has been observed as a semivoluntary action.
  
  Section::::Process.
  
  The upwards wiping of the nose and nostrils allows for running mucus to be wiped off quickly and easily. Also, as the nostrils are being pushed up the air passages through the nose become temporarily propped open. This is especially beneficial if the air passages are swollen and the nostrils are itchy due to irritations such as allergic rhinitis.
   In most cases treatment for rhinorrhea is not necessary since it will clear up on its own—especially if it is the symptom of an infection. For general cases nose-blowing can get rid of the mucus buildup. Though blowing may be a quick-fix solution, it would likely proliferate mucosal production in the sinuses, leading to frequent and higher mucus buildups in the nose. Alternatively, saline nasal sprays and vasoconstrictor nasal sprays may also be used, but may become counterproductive after several days of use, causing rhinitis medicamentosa.
   Sneezing typically occurs when foreign particles or sufficient external stimulants pass through the nasal hairs to reach the nasal mucosa. This triggers the release of histamines, which irritate the nerve cells in the nose, resulting in signals being sent to the brain to initiate the sneeze through the trigeminal nerve network. The brain then relates this initial signal, activates the pharyngeal and tracheal muscles and creates a large opening of the nasal and oral cavities, resulting in a powerful release of air and bioparticles. The powerful nature of a sneeze is attributed to its involvement of numerous organs of the upper body – it is a reflexive response involving the face, throat, and chest muscles.
   Irritation of nerve endings within the nasal passages or airways, can induce a cough reflex and sneezing. These responses cause air to be expelled forcefully from the trachea or nose, respectively. In this manner, irritants caught in the mucus which lines the respiratory tract are expelled or moved to the mouth where they can be swallowed. During coughing, contraction of the smooth muscle in the airway walls narrows the trachea by pulling the ends of the cartilage plates together and by pushing soft tissue into the lumen. This increases the expired airflow rate to dislodge and remove any irritant particle or mucus.
   The nose is also able to provide sense information as to the temperature of the air being breathed, and is an important route for the nasal administration of drugs.
  
  Sneezing is an important protective reflex initiated by irritation of the nasal mucosa to expel unwanted particles through the mouth and nose.
  
  Section::::Function.:Olfaction.
   Sneezing is also triggered by sinus nerve stimulation caused by nasal congestion and allergies.
  
  The neural regions involved in the sneeze reflex are located in the brainstem along the ventromedial part of the spinal trigeminal nucleus and the adjacent pontine-medullary lateral reticular formation. This region appears to control the epipharyngeal, intrinsic laryngeal and respiratory muscles, and the combined activity of these muscles serve as the basis for the generation of a sneeze.
   The relative importance of these three modes of transmission is unclear, and they may all contribute to the spread of the virus. In the airborne route, the droplets that are small enough for people to inhale are 0.5 to 5 µm in diameter and inhaling just one droplet might be enough to cause an infection. Although a single sneeze releases up to 40,000 droplets, most of these droplets are quite large and will quickly settle out of the air. How long influenza survives in airborne droplets seems to be influenced by the levels of humidity and UV radiation: with low humidity and a lack of sunlight in winter probably aiding its survival.
   Although the verb "sneeze" is clearly intransitive, it is conjugated like a transitive verb. In Georgian there are a few verbs like these, and there has not been a clear-cut explanation as to why these verbs have evolved this way. One explanation is that verbs such as "sneeze" used to have a direct object (the object being "nose" in the case of "sneeze") and over time lost these objects, yet kept their transitive behavior.
  
  Section::::Realization of ergativity.:Syntactic ergativity.
   With insufflation, the effects are more abrupt and intense but have a significantly shorter duration, while oral usage results in a milder, longer experience. When insufflated, the onset happens very rapidly, usually reaching the peak at about 20–40 minutes and plateauing for 2–3 hours. 2C-B is also considered one of the most painful drugs to insufflate, with users reporting intense nasal burning. The sudden intensity of the experience combined with the pain can often start the experience with a negative imprint and nausea is also increased with insufflation, compounding the issue.
  
  Section::::Pharmacology.
   In New Zealand, nose pressing ("hongi") is a traditional greeting originating among the Māori people. However it is now generally confined to certain traditional celebrations.
  
  The Hanazuka monument enshrines the mutilated noses of at least 38,000 Koreans killed during the Japanese invasions of Korea from 1592 to 1598.
  
  The septal cartilage can be destroyed through repeated nasal inhalation of drugs such as cocaine. This, in turn, can lead to more widespread collapse of the nasal skeleton.
   Allergic salute
  
  The allergic salute (sometimes called the nasal salute) is the characteristic and sometimes habitual gesture of wiping and/or rubbing the nose in an upwards or transverse manner with the fingers, palm, or back of the hand. It is termed a "salute" because the upward movement of the hand acts as an unintentional gesture. The habit of using the hand to wipe the nose is observed more often in children but is common in adults as well. Saluting most commonly temporarily relieves nasal itching as well as removing small amounts of nasal mucus.
   Blow-ups can also be performed in the symplectic category, by endowing the symplectic manifold with a compatible almost complex structure and proceeding with a complex blow-up. This makes sense on a purely topological level; however, endowing the blow-up with a symplectic form requires some care, because one cannot arbitrarily extend the symplectic form across the exceptional divisor "E". One must alter the symplectic form in a neighborhood of "E", or perform the blow-up by cutting out a neighborhood of "Z" and collapsing the boundary in a well-defined way. This is best understood using the formalism of symplectic cutting, of which symplectic blow-up is a special case. Symplectic cutting, together with the inverse operation of symplectic summation, is the symplectic analogue of deformation to the normal cone along a smooth divisor.
  