Because stable air masses are, by nature, calm and free of violent disturbances, they are often marked by the appearance of stratiform clouds or fog. Stratiform clouds can be identified by their smooth, sheetlike nature and do not build vertically like clouds found in unstable air masses with convective activity.
A) Turbulence and good surface visibility. B) Nimbostratus clouds and good surface visibility.
what conditions cause a stable air mass? To be “unstable“, the lowest layers of an air mass must be so warm and/or humid that, if some of the air rises, then that air parcel is warmer than its environment, and so it continues to rise. This is called moist convection.
One may also ask, what kind of weather is associated with stable air?
Stable air means that the weather is likely to be calm. It may rain or snow slowly and steadily, it may be sunny, but the weather will not change quickly. Unstable air means that the weather might change quickly with very little warning. Unstable air leads to sudden thunderstorms.
Which of the following are characteristics of a moist unstable air mass?
Smooth air, poor visibility, fog, haze, or low clouds. What are characteristics of a moist, unstable air mass? A. Stratiform clouds and showery precipitation.
How can you tell if the atmosphere is stable or unstable?
If the air comes back to where it started, the atmosphere is stable. If the air continues to rise the atmosphere is unstable. In the figure above the air in the parcel has ended up colder and denser than the surrounding air.
What affects air stability?
Adiabatic temperature change is an important factor in determining the stability of the air. We can think of air stability as the tendency for air to rise or fall through the atmosphere under its own “power”. Stable air has a tendency to resist movement. On the other hand, unstable air will easily rise.
What is unstable environment?
The atmosphere is considered to be unstable if a rising parcel cools more slowly than the environmental lapse rate. This causes the air parcel to remain warmer and less dense than its surroundings and, therefore, continue to accelerate upward.
Is there oxygen in the mesosphere?
The percentage of oxygen, nitrogen, and carbon dioxide in the air in the mesosphere is essentially the same as that in the levels of the Earth’s atmosphere immediately above the Earth’s surface. The winds in the stratosphere and mesosphere are usually estimated from temperature data collected by…
Is Rising air stable or unstable?
Air that has a tendency to sink is known as a stable air. If the air parcel’s temperature is greater than the temperature of the surrounding air mass, the air parcel is less dense and tends to rise. Rising air, as we have already learned, is known as unstable.
How does atmospheric instability occur?
Unstable air is warm air that rises, causing atmospheric instability and weather phenomena to occur. Instability is determined by the relative difference in a rising parcel of air and the atmosphere around it, the latter of which naturally cools with altitude due to its environmental lapse rate.
What causes unstable air to stop rising?
orographic lifting. This the most important mechanism for stopping the rise of unstable air parcels: When the environmental lapse rate exceeds both the dry adiabatic lapse rate and the wet adiabatic lapse rate of a parcel of air, that air parcel contains: absolutely unstable air.
What type of clouds are characterized as unstable air?
Cumulus clouds are “heap clouds,” and have a bubbly, or billowy appearance. When the layer of instability in the atmosphere is fairly shallow, clouds are often “fair-weather cumulus” (credit: David Babb) which aren’t very tall because the layer in which air parcels are positively buoyant is fairly thin.
What is absolute instability?
absolute instability. [′ab·s?‚lüt ‚in·st?′bil·?·dē] (meteorology) The state of a column of air in the atmosphere when it has a superadiabatic lapse rate of temperature, that is, greater than the dry-adiabatic lapse rate. Also known as autoconvective instability; mechanical instability.
What determines how much an air parcel will cool?
As a rising parcel cools, its relative humidity increases. Once the relative humidity reaches 100% (determined when the parcel temperature cools down to its original dew point temperature), further lifting (and cooling) results in net condensation, forming a cloud.
What type of clouds are most likely to form in stable air?
b) When heated surface air convects through a stable atmosphere any condensation at height will result in cumulus clouds. In unstable air, heated air can rise to a much greater altitude and cumulonimbus clouds are more likely to form. Precipitation is much more likely to occur from cumulonimbus clouds.
What type of cloud produces tornadoes?
The mesocyclone pulls warm, moist air into a cumulonimbus cloud base, producing a wall cloud. Sometimes the condensation within the wall cloud drops below the base as a rotating funnel. If this funnel cloud touches the ground, it is a tornado.
How do clouds form?
Clouds form when rising air, through expansion, cools to the point where some of the water vapor molecules “clump together” faster than they are torn apart by their thermal energy. Some of that (invisible) water vapor condenses to form (visible) cloud droplets or ice crystals.
What’s the dew point?
The dew point is the temperature to which air must be cooled to become saturated with water vapor. When the temperature is below the freezing point of water, the dew point is called the frost point, as frost is formed rather than dew. The measurement of the dew point is related to humidity.