Have you ever wondered why snow disappears without turning into liquid water? Well, most people think that snow has to melt and then evaporate, but this isn’t always the case.
There are two ways in which snow can disappear, with the most obvious one being melting. Snow can significantly decrease when it gets warmer than 0° Celsius or 32° Fahrenheit.
Snow melting yields water, and it usually happens when humidity level rises or the sun starts shining to warm up the earth’s surface. The melting snow soon turns into a run-off that later evaporates or gets absorbed into the ground.
Now, the other way in which snow disappears is through sublimation. This is a less familiar phase change process that many people don’t think of, and it’s whereby solid water (snow) turns directly into gas.
If you catch yourself wondering if snow can actually evaporate without melting, the answer is yes. Snow can quickly become gas without having to turn into a liquid first.
So, what causes snow to disappear without melting, and how does this process work?
In this article, we’ll talk about how snow changes its state and help you understand the phase change processes better!
How Snow Changes its State
In normal conditions, snow can melt from solid ice to liquid water, which is the natural state of water. The natural state simply means the condition of water under standard pressure and room temperature.
What causes melting is a type of energy known as latent heat, but other factors, such as pressure, determine the heat transfer rate or amount of energy needed to melt the ice.
Under the right conditions, snow will simply change state from solid to liquid as it melts. And if the temperature becomes even warmer, the melted ice will then evaporate into the atmosphere.
But this doesn’t necessarily answer why and how ice typically disappears without becoming liquid water first.
Can Snow Disappear without Melting?
Yes, snow can quickly disappear without melting or leaving a trace!
As we said earlier, the process in which solid ice changes into water is known as melting, and when the liquid water rises into the atmosphere as a gas, it’s called evaporation.
But this is not what always happens to snow. Sometimes the snow disappears without melting, and this is referred to as sublimation.
To know whether the ice is melting or subliming, you can check the amount of water being left as the snow disappears. This can be in the form of a run-off or puddles.
If you notice that the level of snow is reducing and there is not much water running off or forming puddles, it means that most of the ice is sublimating.
You also need to consider other factors, like the type of soil or the ground on which the snow lies. If the ice is in areas that don’t absorb water easily and disappears without melting, it’s subliming.
Let’s have a deeper look at what sublimation means and the conditions in which it happens.
What is Sublimation and How Does It Work on Snow?
Sublimation is whereby a substance transits directly from a solid phase to a vapor phase, skipping the normal liquid state it would pass through under typical temperature and atmospheric pressure.
A good example of sublimation is when solid carbon dioxide (dry ice) is vaporized into carbon dioxide gas directly at normal temperature and atmospheric pressure.
For sublimation to occur, there must be certain combinations of varying factors like latent heat, atmospheric pressure, temperature, wind, and low humidity levels.
The reason is that sublimation requires much more energy than melting, hence such conditions are crucial to catalyze the process.
A major condition for sublimation to happen is the surface temperature, which should be below the melting point (0° Celsius or 32° Fahrenheit).
While latent heat causes a phase change from the solid to the vapor phase, it doesn’t affect the snow temperature. Otherwise, the snow would melt instead of turning into gas if temperature change occurs to it.
Conditions like low atmospheric pressure and dry winds contribute to snow mass loss through sublimation. Dry winds remove the water molecules on snow and release them into the atmosphere.
Does Snow Melt into the Ground?
When it starts getting warmer, snow usually melts from top to bottom. Snow doesn’t melt from the bottom because it has small air pockets that prevent heat from traveling through it.
With such insulation, only the top surface is actually exposed to factors that trigger melting, including direct sunlight, air temperature, humidity, and pressure.
Now, when the ice melts, gravity pulls the water down, forcing it to seep through the snow to the ground. And since there is no heat transfer happening, the flowing water leaves the snow temperature constant.
Depending on the ground on which the snow lies, the liquid water can be absorbed and essentially disappear. This usually happens when the snow lands on surfaces like grass or soil.
However, if the snow has fallen on a hard surface like a roof, car, stone, or any other hard surface, it will become run-off water.
At What Temperature Does Snow Melt and Evaporate?
Snow will start melting at or above (0° Celsius or 32° Fahrenheit), while liquid water can change to solid ice at the same temperature or below.
On the other hand, there is no direct answer to the question of when the snow starts to evaporate. The reason is that liquid water changes to steam at or above 100 °Celsius or 212 ° Fahrenheit.
So, it is between 0 °C or 32 °F and 100 °C or 212 °F that you can typically expect snow to find melting snow (liquid water) and evaporating snow (water vapor). When snow evaporates, the water vapor present is what is usually referred to as humidity.
Generally, phase transitions involve heat, which is either used or released as substances change their state.
Therefore, phase change can have a significantly stabilizing impact on air temperatures that are not near melting and boiling points since evaporation can happen even when the temperature is below the boiling point.
For instance, temperatures in humid climates rarely exceed 35° Celsius since enormous heat or energy is used to evaporate the water into the atmosphere.
In the same way, temperatures in humid weather rarely fall past the point at which the water vapor condenses since much heat is released when condensation happens.
Depending on temperature and weather conditions, snow will melt or disappear within no time. The closer the temperature is to the normal boiling point, the quicker the evaporation and the more water vapor in the atmosphere.
But if the temperature decreases and draws near the freezing point, there will be less evaporation, which means less water vapor in the atmosphere.
With such a wide gap between freezing and boiling temperatures, it’s not easy to determine a specific or universal temperature at which the snow evaporates.
Other than the wide temperature range, there are other factors that affect the snow evaporation process, from humidity levels to sunlight.
High humidity inhibits evaporation since there is more water in the atmosphere. When humidity levels are low, the water molecules in the ice crystals or water will easily evaporate into the air.
If the molecules in snow are able to absorb enough latent heat or energy, they can quickly break the force joining them and evaporate at varied temperatures.
Does Snow Dry Out the Air?
Yes, snow dries out of the air. Cold air cannot hold a lot of moisture, thus, the air is usually dry during the winter months.
Snow is simply precipitation that occurs when there is excess water vapor or moisture in the atmosphere.
When there is enough water vapor in the air, it usually rains, hails, or snows. As the precipitation forms, a lot of water vapor is pulled out from the air, leaving it dry.
With such conditions, many people, especially those participating in winter sports like skiing and snowboarding, experience dry skin and lips.
When you are skiing or snowboarding out there, the cold and dry air sucks the moisture out of your body, leaving you with dry skin and cracked lips.
Sometimes it is almost like you have spent your entire day out on a hot summer day. Your throat may also feel parched as it dries out when your nasal passages open.
Luckily, there are several ways to remediate the effects of dry air in the winter season, and one of the best approaches is to get a humidifier.
If you are going out to ski or snowboard in the winter, you can bring a bottle of water to ensure that you stay hydrated throughout the day.
You can also use moisturizing sunscreen when going out to ride on the slopes to prevent your skin from drying and cracking.
Will Snow Evaporate Below Boiling or Melting Point?
Yes, snow can evaporate even when temperatures are below melting and boiling points. Snow is simply solid water, which has a melting point of 0 °C and a boiling point of 100 °C.
With factors like high humidity and wind, snow can melt into liquid water even at temperatures below the melting point. And when the snow melts, the temperatures don’t have to reach the boiling point or above for it to evaporate.
Snow can quickly evaporate outdoors when there are strong winds or latent heat from sunlight.
What’s even more interesting is that snow can sometimes evaporate without melting in temperatures below melting or boiling points.
But this now becomes sublimation, where the snow disappears into the air without becoming liquid water first.
If evaporation below boiling point and the melting temperature was quite shocking, read on to find out why the snow melts when everything is freezing outdoors.
Why Does the Snow Melt Even When Below Freezing Temperature?
When you are out on the slopes and the snow level seems to be decreasing even with the chilly weather, you can only wonder why the snow melts with temperatures below freezing point.
There are several variables that can cause the snow to disappear even when it’s still cold, and the temperatures are below the freezing point.
First, if the sun is out and there is enough sunlight to provide latent heat to the snow, a good portion of the ice is going to sublimate, and you may not even notice it.
At the beginning of the cold season, snow also melts quickly as it falls, since the ground is still warm for the first few weeks.
In addition, snow hydrologists reveal that snow goes through a settling process as it falls on the ground or other objects.
The settling process involves compressing and getting rid of the air pockets. This way, it might look like a few inches of snow have melted.
Other possible factors that can make the snow melt below the freezing point include heated buildings. If the snow lands on a building being heated, the heat that escapes through the roof will melt the snow.
All in all, the temperature of the snow itself is not always similar to the air temperature surrounding us. So, the next time you see the ice melting below the freezing point, the snow may have absorbed some energy from sunlight to sublime.
Does High Humidity Cause Snow to Melt Faster
Yes, the higher the humidity levels, the faster the snow will melt. The reason is that high humidity levels allow more energy from the surroundings to get into the snow, catalyzing the melting process.
So, more heat is absorbed into the water molecules in the snow when the atmosphere has more moisture. And depending on how much heat transfer occurs, melting can accelerate. But you might wonder, why does this happen?
Well, without getting into much scientific details, the explanation behind this is that heat always wants to settle in a cooler surface or source to balance energy levels and ensure that the surrounding sources have the same heat capacity.
And when this happens, the heat energy in the atmosphere has to move to the snow, which is cooler, causing it to melt from solid ice to liquid water.
It’s like how the ice cubes in a glass of water melt faster than those left exposed to dry air.
With more humidity, sometimes it can rain instead of snow, even when the temperatures are less than the freezing point (0 °C). This also explains why ice that forms at higher elevations melts soon as it falls into a warm and humid environment at low altitudes.
Apart from melting, humidity also affects the nature and structure of the snowflake we get. If there is more moisture in the air, wetter snow will fall, and this may not be the most ideal for skiing.
That’s why most skiers and snowboarders have to wait a few more weeks for quality snow to fall on the slopes after the warm season. Skiers love to ride on fresh, drier powder snow, which usually falls with low humidity and temperatures.
Nonetheless, low humidity levels can cause snow to sublimate, especially on sunny days. The water molecules can absorb enough heat for sublimation even if the sun’s rays have minimized energy as they hit the ground on cold days.
Why Ice Cubes Shrink In the Freezer
What happens to your ice cubes as they age in the freezer is actually the same thing that happens when snow evaporates without melting first.
When you open your freezer and notice that your ice cubes have shrunk, they have probably gone through sublimation. It’s actually the only thing that makes sense unless your freezer is leaky.
In the sublimation process, the water molecules in your ice tray-cooled cubes change directly from a solid phase to a gas phase.
Even so, sublimation requires energy input to break the bond between the water molecules in the ice. But since there is no sunlight or wind in your freezer, the dry cold air can easily suck up the moisture, causing the ice cubes to shrink.
Q: Can Snow Evaporate without Melting?
A: Yes, snow can evaporate without melting through sublimation. This process occurs best during sunny days when the snow can absorb latent heat from the sunlight.
The more exposure to sunlight, the warmer the air in the snow or water molecules becomes, even if the surrounding temperature remains constant.
Other than sunlight, snow can skip the liquid phase by sublimating when there are dry winds. Strong dry winds can help the water molecules in snow evaporate before they get a chance to turn to water first.
Humidity and atmospheric pressure also facilitate snow sublimation. That’s why it often happens at mountain peaks where pressure and humidity are relatively low.
Q: What is it Called When Snow Evaporates Instead of Melting?
A: It’s called sublimation. Sublimation is the process in which substances like ice in the solid phase change to a gaseous state, skipping the liquid phase.
In typical weather conditions, you would expect thermal energy to melt ice first before evaporation happens. This is one of the ways we lose snow, but there is also sublimation.
Direct solid vapor transitions of snow outdoors result from the water molecules absorbing heat from sunlight to overcome the force that holds them together.
But of course, there are other factors that affect phase changes in snow, such as dry winds, humidity, and atmospheric pressure.
Q: Is Melting Snow Evaporation?
A: No, melting snow is not the same as evaporation, but both are processes involved in snow phase change.
In melting, solid ice becomes liquid with the heat absorbed. This liquid is what you normally see as run-off water, which flows off or seeps into the ground, depending on the surface.
On the other hand, evaporation refers to the process in which a liquid changes into a gaseous state. It could also be a solid substance like snow or ice turning into a gas or water vapor, but then the process is known as sublimation.
Q: Does Snow Evaporate or Sublimate?
A: Snow can evaporate or sublimate under certain conditions. Evaporation usually happens when the snow becomes liquid water and then vanishes as the temperature rises.
On the flip side, sublimation occurs when the snow changes from a solid state to a gas phase without going through the liquid phase.
If you want to find out whether the snow in your area evaporates or sublimates, you can check the surface. If there is no flowing water and the snow mass seems to decrease, the ice is going through sublimation.
But you also need to consider other things like the type of surface the snow falls on since soft ground like soil and grass will quickly absorb the melted ice before evaporation happens.
Q: Does Dry Ice Have High Equilibrium Vapor Pressure?
A: While most solids have very low equilibrium vapor pressure, dry ice has high vapor pressure. The pressure is high when its sublimation rate matches its vapor state disposition.
Frozen carbon dioxide can quickly sublime at normal or even freezing temperatures (at −78.5 °C) or (−109.3 °F) since its molecules can overcome their intermolecular attraction with other particles.
Q: Why Does Dry Ice (Solid Carbon Dioxide) Go Straight to Gas?
A: Dry ice usually transits from a solid phase directly to a gaseous phase since carbon dioxide exists as a gas at normal pressure and room temperature.
When you expose dry ice to normal conditions, it sublimes to return to a gas phase, which is the typical carbon dioxide state.
Since frozen carbon dioxide is a highly volatile compound, you shouldn’t keep it in your fridge or walk-in freezer. Instead, you should always store it in non-air-tight containers like coolers with adequate insulation for safety and slowing down sublimation.
Keep in mind that frozen carbon dioxide will start subliming at any temperature above -109. 3° F. It will vanish quickly even when stored in a freezer since the temperature is still high to prevent it from sublimating.
Snow will inevitably disappear as the weather starts warming up. It usually disappears through the melting process, whereby the snow changes into liquid water and then evaporates or flows as run-off water.
But this isn’t the only process since snow can evaporate instead of melt. There is another process known as sublimation that causes snow to evaporate without melting.
With the right conditions like latent heat, low atmospheric pressure, and high-speed dry winds, sublimation can quickly cause the snow to disappear in front of your eyes.
If you want to know whether the snow is melting or evaporating, you can check the surface below the snow mass. If no water flows and the snow reduces, sublimation is probably happening!