A stable air mass is one in which there is warm air overlying cold air . Why is that called stable? It is stable because if something should bump the underlying cold air and push it up, the colder air, being more dense than the air above it, will sink right back down to the ground.
What determines whether air is stable or unstable?
What makes air stable or unstable? 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.
What type of conditions are associated with stable air?
Weather is strongly affected by how stable or unstable the atmosphere is. 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.
What are 4 ways that air can be forced upward?
– There are four lifting mechanisms that form clouds: Orographic Lifting, Convection, Convergence, and Updraft . – Orographic lifting is when air cannot go through a mountain, and so it flows over it. – Frontal Lifting is when less dense warm air is forced to rise over cooler, denser air as a weather fronts move.
What two conditions working together make the atmosphere the most unstable?
The difference between the cold parcel air and the warmer surroudings gets larger and larger with increasing altitude. 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 atmosphere is stable?
In order to determine the stability of the atmosphere, meteorologists compare the temperature of a rising air parcel with the temperature of the air around it at the same level . To describe the temperature of the atmosphere surrounding air parcels, meteorologists use the environmental lapse rate.
What does it mean when an air mass is unstable?
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.
Which lapse rates are compared to determine the stability of the atmosphere?
A temperature lapse rate less than the dry adiabatic rate of 5.5°F. per 1,000 feet for an unsaturated parcel is considered stable, because vertical motion is damped.
What are two things that can force air to rise quickly?
- Surface heating and free convection. During the daytime, the earth’s surface is heated by the sun, which in turn heats the air in contact with the surface. ...
- Surface Convergence and/or Upper-level Divergence. ...
- Lifting Due To Topography. ...
- Lifting Along Frontal Boundaries.
What are the three conditions reasons that causes air to rise?
- Surface heating and free convection.
- Horizontal Convergence of surface air and/or Horizontal Divergence of air near the top of the troposphere.
- Topography (mountains)
- Uplift along weather fronts.
What causes air to rise up?
Hot air rises because gases expand as they heat up . When air heats up and expands, its density also decreases. The warmer, less dense air effectively floats on top of the colder, denser air below it. This creates a buoyant force that causes the warmer air to rise.
Which factor is most significant in the formation of clouds in the atmosphere?
Condensation is the process by which water vapor in the air is changed into liquid water. Condensation is crucial to the water cycle because it is responsible for the formation of clouds.
Which condition below would make a layer of air more unstable?
When a layer of air is forced to rise it tends to become more unstable because the top layer cools more rapidly than the bottom. This steepens the environmental lapse rate. This effect is enhanced even more when the lower layer of the lifted parcel is moist and the upper layer is dry.
What is a stable atmosphere and how can it form?
The atmosphere is considered to be stable if a rising parcel cools faster than the environmental lapse rate . This causes the air parcel to be cooler and more dense than its surroundings and, therefore, lose its buoyancy.
What is the lapse rate of atmosphere?
The dry adiabatic lapse rate for the Earth’s atmosphere equals 9.8 °C per kilometre (28.3 °F per mile); thus, the temperature of an air parcel that ascends or descends 5 km (3 miles) would fall or rise 49 °C (85 °F), respectively.
What is an indicator of stable air?
Indicators of a stable atmosphere are steady winds, clouds in layers, and poor visibility due to haze and smoke hanging near the ground . Unstable conditions are indicated by dust devils, gusty winds, clouds with vertical growth, and good visibility. (
