Cumulus and cumulonimbus convection

Ludlam, F. H.

doi:10.1111/j.2153-3490.1966.tb00290.x

Cited by 26 publications

(16 citation statements)

References 21 publications

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“…Indeed, collaboration between t h e various scales of atmospheric convection, a subject examined thoroughly b y Ludlam (1966), is a n essential part of the global tropospheric circulation. South-west Asia possesses geographical features which are apparently of considerable significance in t h e monsoon system of southern Asia.…”

Section: Resultsmentioning

confidence: 99%

On summer atmospheric processes over south-west Asia

Walker

1975

Tellus A: Dynamic Meteorology and Oceanography

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Section: Resultsmentioning

confidence: 99%

On summer atmospheric processes over south-west Asia

Walker

1975

Tellus A: Dynamic Meteorology and Oceanography

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“…Also, the ®s minimum level is an indicator of cumulus cloud tops [16] and for the IGY period, this minimum in the mean, exists around the 500 mb level. The parcel is then brought down moist adiabatically to the 1000 mb level where ®wp value is read.…”

Section: A Potential Instability Index Pmentioning

confidence: 99%

Potentielle Instabilität und Vorkommen von Niederschlag im Bereich der Intertropischen Diskontinuität

Adedokun

1981

Arch. Met. Geoph. Biocl. A.

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The degree of potential instability along a transect around the longitude of Lagos running through the Intertropical Discontinuity (ITD) is investigated using an instability index P which is similar to but not the same as the Showalter Index. Over 200 radiosonde/rawinsonde observations made over Lagos, Niamey and Aoulef in West Africa during the IGY, in particular, 1958, are used to investigate the variation of P across the ITD. Places north, over and up to 2 ° of latitude south of the ITD are predominantly stable even during the Monsoon (rainy) months considered. The cases of instability found are located farther (i. e. greater than 2 °) south of the ITD than the precipitation. Contingency tables give a better credence to a modified form of the index, styled P j, and suggest that the Showalter stability index does not work over the region. Potential instability alone is not a sufficient condition for precipitation, however, and the role of the large scale circulation in arranging a "triggering mechanism" should be considered. Zusammenfassung Potentielle Instabilit/it und Vorkommen yon Niederschlag im Bereich tier Intertropischen Diskontinuit/itDer Grad der potentiellen Instabilit~it im in der L/rage von Lagos die Intertropische Diskontinuit/~t (ITD) tiberquerenden Schnitt wird mit Verwendung eines Instabilit/~tsindexP, der dem Showalter-Index ~ihnlich ist, untersucht. ~2ber 200 Radiosonden-Beobachtungen tiber Lagos, Niamey und Aoulef in West-Afrika aus dem IGY wurden zur Untersuchung der ~nderung yon P quer durch die ITD verwendet. N6rdlich und bis zu 2 Grad Breite stidlich der ITD ist Stabilit/it auch w/ihrend der Monsunmonate vorherrschend, lnstabilit~iten mit Niederschlag wurden um raehr als 2 Grad welter stidlich der ITD gefunden. Kontingenz-Tabelien erweisen ein besseres Vertrauen zu dem modifizierten Index, der mit Pj bezeichnet wird, und zeigen, daf~ der Showalter-Stabilit~itsindex in dieser Region

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“…The observed effects of these cloud fields on the layer beneath bring to mind Ludlam's (1966) discussion of stratification of a cumulus layer and the associated heat fluxes. From this basis, Betts (1973) developed a parametric treatment of the area-averaged properties of a cumulus layer; the features relevant to the present argument may be briefly summarized as follows.…”

Section: Cloud-base Heat and Moisture Transfermentioning

confidence: 99%

Diurnal evoluion of properties of the sub-cloud layer over land

Coulman

1980

Boundary-Layer Meteorol

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Observations of temperature, humidity and velocity structure beneath fields of cumulus clouds are analysed with the needs of cloud modelhng and cloud field parameterization in mind. Sub-cloud fluxes of sensible and latent heat and their diurnal variations are determined from layer-mean profiles and from eddy-correlation measurements; the latter are especially sensitive to sampling on cloud-sized scales. The characteristic fluctuations in velocity temperature and humidity beneath clouds have time scales like the lifetime typical of small cumulus clouds: there is no evidence that such fluctuations occur only as brief pulses at cloud initiation. The magnitudes of these fluctuations exhibit well-marked diurnal patterns of change.

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Cumulus and cumulonimbus convection

Cited by 26 publications

References 21 publications

On summer atmospheric processes over south-west Asia

On summer atmospheric processes over south-west Asia

Potentielle Instabilität und Vorkommen von Niederschlag im Bereich der Intertropischen Diskontinuität

Diurnal evoluion of properties of the sub-cloud layer over land

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