325:
convection. There is a major limitation of this measure of stability however, which is that it does not take the thermodynamic properties (saturation mixing ratio and therefore the shape of adiabats in the lower troposphere) of the air into account. A more refined measure of stability has since been developed, named the estimated inversion strength, which pays closer attention to the thermodynamic properties of the air in the lower troposphere.
34:
172:
is released into the air parcel. Moist air has more water vapor than dry air, so more latent heat is released into the parcel of moist air as it rises. Dry air does not have as much water vapor, therefore dry air cools at a higher rate with vertical movement than moist air. As a result of the latent
184:
and temperature determine the stability of the air and the resulting weather. Cool, dry air is very stable and resists vertical movement, which leads to good and generally clear weather. The greatest instability occurs when the air is moist and warm, as it is in the tropical regions in the summer.
159:
When air rises, moist air in which condensation has occurred cools at a lower rate than dry air (including moist air in which condensation has not yet occurred). That is, for the same upwards vertical movement and starting temperature, a parcel of moist air will be warmer than a parcel of dry air.
324:
that caps the planetary boundary layer on earth, and also indicates the level of convective stability of an air column at a given location. Regions with negative LTS have a larger potential temperature on the surface than in the mid-troposphere, which makes the air column unstable and encourages
177:). The dry adiabatic lapse rate (for unsaturated air) is 3 °C (5.4 °F) per 1,000 vertical feet (300 m). The moist adiabatic lapse rate varies from 1.1 to 2.8 °C (2.0 to 5.0 °F) per 1,000 vertical feet (300 m).
27:
107:
cooling and heating are phenomena of rising or descending air. Rising air expands and cools due to the decrease in air pressure as altitude increases. The opposite is true of descending air; as
255:
173:
heat that is released during water vapor condensation, moist air has a relatively lower adiabatic lapse rate than dry air. This makes moist air generally less stable than dry air (see
284:
555:
315:
118:
The adiabatic lapse rate is the rate at which the temperature of a rising or falling air mass lowers or increases per distance of vertical displacement. The ambient or
80:, where an air mass is displaced upwards as it is blown by wind up the rising slope of a mountain range) tend to become larger, resulting in turbulent airflow and
380:
188:
The ambient lapse rate differs in different meteorological conditions, but, on average, is 2 °C (3.6 °F) per 1,000 vertical feet (300 m).
999:
548:
697:
174:
115:
of descending air increases as it is compressed. Adiabatic heating and adiabatic cooling are terms used to describe this temperature change.
20:
994:
717:
541:
409:
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is the temperature change in the (non-displaced) air per vertical distance. Instability results from difference between the
399:
712:
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907:
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196:
Lower tropospheric stability (commonly referred to as LTS) is a meteorological parameter that is commonly used in
887:
821:
649:
185:
Typically, thunderstorms appear on a daily basis in these regions due to the instability of the surrounding air.
451:
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relative to the atmosphere. As cooler air is more dense, the rise of such an airmass would tend to be resisted.
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relative to the atmosphere. As warmer air is less dense, such an air mass would tend to continue to rise.
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483:"On the Relationship between Stratiform Low Cloud Cover and Lower-Tropospheric Stability"
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442:
892:
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33:
37:
Convective
Instability, denoted in the red highlighted region ("positive area"), on a
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It was first introduced as a simple but useful measure of the strength of the
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rapidly than the air in which it is moving. Hence, such an air mass becomes
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rapidly than the air in which it is moving. Hence, such an airmass becomes
965:
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841:
586:
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58:
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in the air parcel due to expansion cooling. As water vapor condenses,
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makes vertical movement difficult, and small vertical disturbances
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401:
Encyclopedia of
Weather and Climate, Revised Edition, 2-Volume Set
32:
621:
200:. It is computed at a given location on Earth and is defined as
148:
than the ambient lapse rate, an air mass displaced upward cools
133:
than the ambient lapse rate, an air mass displaced upward cools
537:
654:
126:
of an air mass and the ambient lapse rate in the atmosphere.
452:
10.1175/1520-0442(1993)006<1587:TSCOLS>2.0.CO;2
481:
Wood, Robert; Bretherton, Christopher S. (December 2006).
19:
For a more general discussion of the same phenomenon, see
425:
Klein, Stephen A.; Hartmann, Dennis L. (August 1993).
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208:
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of an air parcel at the 700 hPa pressure level, and
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778:
688:
635:
569:
61:refers to its ability to resist vertical motion. A
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16:Ability of an air mass to resist vertical motion
76:atmosphere, vertical air movements (such as in
28:public domain text created by the US government
250:{\displaystyle LTS=\theta _{700}-\theta _{0},}
84:activity. Instability can lead to significant
549:
427:"The Seasonal Cycle of Low Stratiform Clouds"
317:is the potential temperature at the surface.
8:
698:Convective available potential energy (CAPE)
404:. Sonlight Christian -m. pp. 435–436.
144:Conversely, if the adiabatic lapse rate is
556:
542:
534:
398:Allaby, Michael; Garratt, Richard (2007).
381:United States Department of Transportation
376:Pilot's Handbook of Aeronautical Knowledge
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450:
301:
295:
270:
264:
238:
225:
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359:
175:convective available potential energy
21:Convective available potential energy
7:
660:Convective condensation level (CCL)
866:Equivalent potential temperature (
14:
718:Conditional symmetric instability
564:Meteorological data and variables
347:Conditional symmetric instability
88:, extensive vertical clouds, and
665:Lifting condensation level (LCL)
650:Cloud condensation nuclei (CCN)
385:Federal Aviation Administration
129:If the adiabatic lapse rate is
913:Wet-bulb potential temperature
755:Level of free convection (LFC)
1:
1000:Severe weather and convection
956:Pressure-gradient force (PGF)
878:Sea surface temperature (SST)
713:Convective momentum transport
387:. 2016. pp. 12–12–12–13.
279:{\displaystyle \theta _{700}}
770:Bulk Richardson number (BRN)
192:Lower tropospheric stability
974:Maximum potential intensity
740:Free convective layer (FCL)
703:Convective inhibition (CIN)
310:{\displaystyle \theta _{0}}
1016:
995:Atmospheric thermodynamics
908:Wet-bulb globe temperature
765:Maximum parcel level (MPL)
26:This article incorporates
25:
18:
888:Thermodynamic temperature
822:Forest fire weather index
72:out and disappear. In an
810:Equivalent temperature (
723:Convective temperature (
607:Surface weather analysis
120:environmental lapse rate
857:Potential temperature (
602:Surface solar radiation
160:This is because of the
847:Relative humidity (RH)
735:Equilibrium level (EL)
708:Convective instability
311:
280:
251:
51:convective instability
42:
335:Free convective layer
312:
288:potential temperature
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36:
936:Atmospheric pressure
903:Wet-bulb temperature
805:Dry-bulb temperature
800:Dew point depression
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263:
206:
124:adiabatic lapse rate
109:atmospheric pressure
39:Skew-T log-P diagram
898:Virtual temperature
883:Temperature anomaly
577:Adiabatic processes
499:2006JCli...19.6425W
443:1993JCli....6.1587K
198:atmospheric physics
180:The combination of
670:Precipitable water
508:10.1175/JCLI3988.1
487:Journal of Climate
431:Journal of Climate
307:
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78:orographic lifting
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951:Pressure gradient
760:Lifted index (LI)
493:(24): 6425–6432.
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437:(8): 1587–1606.
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368:"Weather Theory"
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893:Vapor pressure
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90:severe weather
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946:Barotropicity
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675:Precipitation
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852:Mixing ratio
827:Haines Index
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637:Condensation
522:22 September
520:. Retrieved
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466:22 September
464:. Retrieved
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341:Lifted index
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162:condensation
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941:Baroclinity
788:Dew point (
780:Temperature
680:Water vapor
170:latent heat
166:water vapor
113:temperature
47:meteorology
989:Categories
918:Wind chill
832:Heat index
690:Convection
627:Wind shear
612:Visibility
592:Lapse rate
354:References
86:turbulence
82:convective
66:atmosphere
617:Vorticity
597:Lightning
582:Advection
322:inversion
299:θ
268:θ
236:θ
232:−
223:θ
105:Adiabatic
100:Mechanism
55:stability
966:Velocity
928:Pressure
842:Humidity
745:Helicity
587:Buoyancy
517:18011630
461:26198436
329:See also
182:moisture
92:such as
74:unstable
59:air mass
837:Humidex
750:K Index
570:General
495:Bibcode
439:Bibcode
286:is the
515:
459:
408:
259:where
154:cooler
146:higher
139:warmer
70:dampen
63:stable
57:of an
645:Cloud
513:S2CID
457:JSTOR
371:(PDF)
349:(CSI)
337:(FCL)
131:lower
622:Wind
524:2022
468:2022
406:ISBN
343:(LI)
150:more
135:less
655:Fog
503:doi
447:doi
272:700
227:700
164:of
53:or
45:In
991::
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871:e
868:θ
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859:θ
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815:e
812:T
795:)
793:d
790:T
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728:c
725:T
557:e
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449::
441::
435:6
414:.
303:0
245:,
240:0
219:=
216:S
213:T
210:L
41:.
30:.
23:.
Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.
