Short Answer. The breath feels warm when blown out of an open mouth because the air is moving slower and can't remove heat from surfaces effectively, whereas it feels cold when blown through a smaller opening due to increased air speed which leads to more effective heat removal from surfaces.
When you breath out quickly through a small opening there is higher pressure in your lungs and mouth than there is outside, and then an abrupt pressure drop as it exits, causing it to cool. I noticed this same effect yesterday after using my air compressor.
Exhaled air is warmer and cleaner than inhaled air. Oxygen The percentage of Oxygen in exhaled air is less than in inhaled air because the body uses Oxygen for respiration Carbon Dioxide The percentage of carbon dioxide increases when exhaling as it is a product of respiration. So, exhaled air is hotter and cleaner.
``hoo'' causes air to build up pressure in your mouth before it gets released at a lower pressure, and according to Gay-Lussac's Law, a decrease in pressure causes a decrease in temperature. ``haa'' releases air at around the same pressure it was in your lungs, so it stays warm.
When you blow out with an open mouth, the air expelled has a lower speed and does not carry away heat from your skin quickly. As a result, you feel the warm air that is expelled from your lungs which are heated to your body's internal temperature.
According to pulmonologist Dr. Michael Scharf, inhaling cold air may cause bronchial irritation and cough. If you have asthma or chronic obstructive pulmonary disease (COPD), the cold air “may induce bronchial tightening or constriction leading to cough, wheeze and shortness of breath.”
The reason is because as wind blows across our bodies it takes the heat we naturally emit and blows it away from our bodies. The faster the wind speed the faster our body heat is taken away and the colder it feels. It is a similar process for when you blow on a hot bowl of soup to cool it down.
- Cold Front: A cold front occurs when a cold air mass moves into an area of warmer air. As the cold air displaces the warm air, it pushes it upward, creating a steep slope. This can result in the formation of cumulonimbus clouds and potentially severe weather, such as thunderstorms, heavy rain, and strong winds.
The pres- sure of the atmosphere drops with altitude, by about 10 kPa (100 millibar) per 1000 m. As a rising parcel of air moves into regions of lower pressure, it expands. And as it expands, it cools.
Breathe in oxygen, Breathe out…
And when you breathe out (exhale), your lungs put carbon dioxide back into the air. However, the breath you exhale doesn't only contain carbon dioxide. It also contains moisture from your mouth and lungs. This moisture is in the form of water vapor, the gas form of water.
When you inhale (breathe in), air enters your lungs, and oxygen from that air moves to your blood. At the same time, carbon dioxide, a waste gas, moves from your blood to the lungs and is exhaled (breathed out). This process, called gas exchange, is essential to life.
Keep your palm in front of the mouth and blow some air. It will feel warm. This proves that the air that is breathed out is warmer. In place of the hand, we can also place a folded handkerchief, we can feel that the place where we breathe out is warmer than the area which was not in contact with your breathe.
When you exhale when it's cold outside, the water vapour in your breath condenses into lots of tiny droplets of liquid water and ice (solid water) that you can see in the air as a cloud, similar to fog which appears smoke like. This process is called condensation.
Cold air is generally drier, and your body works to humidify this. In that process, it can cause irritation to the airways, which results in a process called bronchospasm, where those airways narrow and tighten, and you get that feeling of shortness of breath.
Exhaled air usually is warmer than ambient temperature. Air in the lungs is warmed by core body heat, thereby creating a temperature difference between air entering and exiting the respiratory system.
A stationary front forms when a cold front or warm front stops moving. This happens when two masses of air are pushing against each other, but neither is powerful enough to move the other. Winds blowing parallel to the front instead of perpendicular can help it stay in place. A stationary front may stay put for days.
When warm air meets cold air the air is reduced below its saturation point and as a result water vapour turns from a gas into a liquid. This can be visually observed on window sills, tiles etc. This is known as surface condensation.
At dew point, air can no longer hold water vapor; when air is cooled beyond dew point water vapor turns to liquid form, the physical process known as condensation. It is this liquid form of your breath – minuscule droplets of water – that creates the fleeting, misty cloud we see when breathing in cold weather.
The fast moving air increases the rate at which our bodies lose heat due to convection and evaporation. The faster moving air from the fan displaces the warmer air that is in direct contact with our skin. This enhances the rate of convective heat transfer, which means we feel cooler.
We are much more likely to feel the cold when our skin is wet. That's because body heat escapes much more easily through wet skin.
The biggest changes are the renaming of the wind chill watches and warnings and the wind chill advisories. The wind chill watch and warning will be replaced with "Extreme Cold Watch" and "Extreme Cold Warning" as shown below with the explanation.
"Exhaled breath temperature has been proven to be an indicator of airway inflammation and increased vascularity.
States along the Mississippi and Ohio rivers have the highest COPD prevalence. State prevalence rates range from 3.7% in Hawaii to 13.6% in West Virginia.
“[We have] shown that increasing warmth leads to improvements in health for most respiratory diseases, and our recently completed Housing, Heating and Health Study found warmer temperatures improved the respiratory symptoms of children with asthma,” she says.