How does the path an air mass follows affect stability?
The path an air mass follows determines the stability in the upper levels of the air mass. The flow of an air mass around the subpolar lows decreases stability which enhances weather because of the upward vertical motion. It is given stability indicator of “u”.
What is the function of the Mt air mass?
The mT air mass provides moisture for mush of the central United States. The path an air mass follows determines the stability in the upper levels of the air mass. The flow of an air mass around the subpolar lows decreases stability which enhances weather because of the upward vertical motion.
What do unstable and stable air masses look like?
What do stability and instability look like? The clearest way to observe the difference between a stable and an unstable air mass is to look at the clouds: A stable atmosphere will have largely flat layers of cloud, which may exhibit some lumpiness but will not extend far upwards. There may be several such layers or, occasionally, clear skies.
How do atmospheric forces affect an air mass?
There are several atmospheric forces that effect an air mass as it moves from its source region. These forces show up as the air mass is being modified and can determine the severity of the weather associated with the air mass. Warm air wants to rise and cold air want to sink due to the different densities.
Which would decrease the stability of an air mass?
The stability of an air mass decreases when its lower layers become warm and sometimes humid, making the mass warmer than its environment and causing it to rise.
What is air mass stability?
Air mass having a stable stratification in its lower layer, and consequently free from convection, having a low degree of turbulence, and containing either stratiform clouds, fog, or no clouds at all.
Which is a characteristic typical of a stable air mass?
Stable air masses are also characterized by smooth, undisturbed air. This quality can be seen mainly by pilots or air travelers. People flying through stable air masses will not experience violent turbulence or disturbances as they would in unstable air masses.
What causes stable air?
The atmosphere is said to be absolutely stable if the environmental lapse rate is less than the moist adiabatic lapse rate. This means that a rising air parcel will always cool at a faster rate than the environment, even after it reaches saturation.
How is the stability of air determined quizlet?
In general, we determine the stability of air by comparing a rising parcel's temperature to that parcel's surroundings. An air parcel will rise in the atmosphere when its density is less than the density of its surroundings.
How can you determine the stability of an air mass quizlet?
Indicates stability: stability of the atmosphere is determined by vertical movements of air. Warm air rises when the air above is cooler. Cooling from below: surrounding air is warmer, which would increase the stability of an air mass.
Which of the following is a characteristic of stable air?
Explanation: characteristics of stable air: stratiform clouds, continuous precipitation, smooth air, poor visibility.
How can the atmosphere be made more stable more unstable?
Sunlight warms the ground and the air next to it during the day. This steepens the environmental lapse rate and makes the atmosphere more unstable. Cooling air above the ground has the same effect.
How do you know if air 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.
Which of the following would best create a stable atmosphere?
Which of the following would best create a stable atmosphere? air moving from a large body of land to a large body of water.
What is air mass simple definition?
An air mass is a large volume of air in the atmosphere that is mostly uniform in temperature and moisture. Air masses can extend thousands of kilometers across the surface of the Earth, and can reach from ground level to the stratosphere—16 kilometers (10 miles) into the atmosphere.
What does unstable air mass mean?
Air is considered unstable, in the lowest layers of an air mass when the air is warmer and or more humid than the surrounding air. When this occurs the air will rise, as that air parcel is warmer than the air surrounding it. In an unstable environment, the weather can change suddenly and can be violent.
What is the difference between a stable and unstable air mass?
If it falls rapidly with height, the atmosphere is said to be unstable; if it falls more slowly (or even temporarily increases with height), a stable atmosphere is present.
What does stable air mean?
Atmospheric stability is defined as the resistance of the atmosphere to vertical motion. A stable atmosphere resists an upward or downward movement. An unstable atmosphere allows an upward or downward disturbance to grow into a vertical (convective) current.
What happens when water is warmer than air?
When the water is warmer than the air, evaporation can raise the dew point sufficiently to saturate the air and form stratus or fog.
How are air masses modified?
Some ways air masses are modified are: (1) warming from below, (2) cooling from below, (3) addition of water vapor, and (4) subtraction of water vapor:
How is water vapor removed?
Water vapor is removed by condensation and precipitation.
What is FIGURE 58?
FIGURE 58. Horizontal uniformity of an air mass. (Properties of air at A1, A2, etc., are about the same as those at A; properties at B1, B2, etc., are about the same as those at B.)
When a body of air comes to rest or moves slowly over an extensive area having fairly uniform properties of temperature and moisture?
When a body of air comes to rest or moves slowly over an extensive area having fairly uniform properties of temperature and moisture, the air takes on those properties. Thus, the air over the area becomes somewhat of an entity as illustrated in figure 58 and has fairly uniform horizontal distribution of its properties. The area over which the air mass acquires its identifying distribution of moisture and temperature is its “source region.”
What happens when cool air moves over a warm surface?
Cool air moving over a warm surface is heated from below, generating instability and increasing the possibility of showers.
What causes April showers?
Those April Showers made famous by the rhyme, are therefore the result of instability in the atmosphere together with a trigger to get them started. However, in reality, things are a little more complicated. For a start, the value of the adiabatic lapse rate is not constant, depending upon both the temperature itself and whether or not cloud is forming as the parcel rises. Then, there is the intermediate position between stability and instability; a phenomenon known as conditional instability. That is when the atmosphere is essentially stable, up until something happens to flip the situation into an unstable one. But more of that in a future post……
What is the graph of height against temperature?
Image 1: Graph of height against temperature in a stable situation with a temperature inversion (a layer in which the atmosphere warms with height). The air ‘parcel’ starts off warmer than the atmosphere at low levels and therefore it rises.
How to tell if air is stable?
It is the vertical profile of temperature, or lapse rate of the atmosphere, which determines whether an air mass is stable or not. The temperature can be measured using an electronic thermometer attached to a helium-filled weather balloon released from the ground. As it ascends, the readings are transmitted back to earth and, under normal circumstances, the temperature would be found to fall with height. But it does not always fall at the same lapse rate. If it falls rapidly with height, then the atmosphere is said to be unstable; if it falls more slowly (or even temporarily increases with height) then a stable atmosphere is present.
What is stable atmosphere?
A stable atmosphere will have largely flat layers of cloud which, although they may exhibit some lumpiness, will not extend far upwards. There may be several such layers or occasionally, clear skies.
How does air rise?
There are several mechanisms by which air can be encouraged to start rising. These include: 1 Heating from below: If air is located over a surface which is warmer than it is, then it will be heated by the surface. This will make it less dense and it will start to rise 2 Coasts and hills: Physical barriers to air flow will force air to rise over them 3 Convergence: If two air flows meet from different directions, then one may be forced to rise over the other 4 Weather fronts: Rising air is associated with weather fronts
What happens when air is heated?
Heating from below: If air is located over a surface which is warmer than it is, then it will be heated by the surface. This will make it less dense and it will start to rise
Is adiabatic lapse rate constant?
For a start, the value of the adiabatic lapse rate is not constant, depending upon both the temperature itself and whether or not cloud is forming as the parcel rises. Then, there is the intermediate position between stability and instability; a phenomenon known as conditional instability.
