A simplified model for the formation, movement, and dissipation of fair weather cumulus clouds

1965 ◽  
Vol 2 (1) ◽  
pp. 178-185
Author(s):  
Martin Fox
Keyword(s):  
Stochastic Model ◽  
Cloud Cover ◽  
Temporal Evolution ◽  
Cooling Effect ◽  
Simplified Model ◽  
Fair Weather ◽  
Cumulus Clouds ◽  
Solar Heat

Certain patches of ground are favorable to the formation of fair weather cumulus clouds. These are patches which reflect rather than absorb solar heat. As the air above these patches is warmed, it will rise and, if the humidity is sufficient, the cooling effect of higher elevation will cause formation of a cloud of the type known as the fair weather cumulus. This fact is used in the present paper to develop a stochastic model for the temporal evolution of the contribution to cloud cover by fair weather cumuli.

A simplified model for the formation, movement, and dissipation of fair weather cumulus clouds

1965 ◽  
Vol 2 (01) ◽  
pp. 178-185
Author(s):  
Martin Fox
Keyword(s):  
Stochastic Model ◽  
Cloud Cover ◽  
Temporal Evolution ◽  
Cooling Effect ◽  
Simplified Model ◽  
Fair Weather ◽  
Cumulus Clouds ◽  
Solar Heat

Certain patches of ground are favorable to the formation of fair weather cumulus clouds. These are patches which reflect rather than absorb solar heat. As the air above these patches is warmed, it will rise and, if the humidity is sufficient, the cooling effect of higher elevation will cause formation of a cloud of the type known as the fair weather cumulus. This fact is used in the present paper to develop a stochastic model for the temporal evolution of the contribution to cloud cover by fair weather cumuli.

scholarly journals Aerosols Make Cumulus Clouds Brighter but Shorter Lived

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
David Shultz
Keyword(s):  
Computer Simulations ◽  
Cloud Cover ◽  
Aerosol Particles ◽  
Cooling Effect ◽  
Cumulus Clouds

Computer simulations show that although adding aerosol particles to clouds can make them more reflective, the cooling effect from clouds is largely counterbalanced by a reduction in overall cloud cover.

scholarly journals The Relationship Between Cloud Cover and Outgoing Longwave Radiation in the Southern of Vietnam

2018 ◽  
Vol 34 (1S) ◽  
Author(s):  
Chu Thi Thu Huong ◽  
Bui Thi Hop ◽  
Tran Dinh Linh ◽  
Vu Thanh Hang
Keyword(s):  
Spatial Distribution ◽  
Rainy Season ◽  
Outgoing Longwave Radiation ◽  
Cloud Cover ◽  
Temporal Evolution ◽  
El Nino ◽  
Longwave Radiation ◽  
Downward Trend ◽  
La Nina ◽  
The Relationship

Abstract: Based on the data that has the resolution is 1,00×1,00of the Outgoing Longwave Radiation (OLR) and the cloud cover from NCEP/NCAR in the 1981 – 2012 period, the relationship between the cloud cover and the OLR in the Southern of Vietnam wasinvestigated when analyze and compare the spatial distribution, temporal evolution and their correlation. The results show that the characteristics of the spatial distribution and the year cycle of cloud cover and OLR are inversely correlated. The region or time that the cloud cover is great, the OLR is small and vice versa. In the Southern of Vietnam, the OLR value isgreatest(or smallest) in the dry (or rainy) season and in the El-Nino (La-Nina) years. In addition, during the 1981-2012period, the OLR in this region shows a downward trend about 3.6 W/m2/decade, while the cloud cover tends to increase by 0.2%/decade. Keywords: Cloud cover, Outgoing Longwave Radiation, the Southern of Vietnam.

scholarly journals Influence of fair-weather cumulus clouds on isoprene chemistry

2012 ◽  
Vol 117 (D10) ◽  
pp. n/a-n/a ◽  
Author(s):  
S.-W. Kim ◽  
M. C. Barth ◽  
M. Trainer
Keyword(s):  
Fair Weather ◽  
Cumulus Clouds

scholarly journals A Simple Parameterization Coupling the Convective Daytime Boundary Layer and Fair-Weather Cumuli

2005 ◽  
Vol 62 (6) ◽  
pp. 1976-1988 ◽  
Author(s):  
Larry K. Berg ◽  
Roland B. Stull
Keyword(s):  
Boundary Layer ◽  
Cloud Cover ◽  
Potential Temperature ◽  
Joint Probability ◽  
Cloud Base ◽  
Cumulus Clouds ◽  
Eddy Simulation ◽  
Boundary Layer Cloud ◽  
Using Data ◽  
Water Vapor Mixing Ratio

Abstract A new parameterization for boundary layer cumulus clouds, called the cumulus potential (CuP) scheme, is introduced. This scheme uses joint probability density functions (JPDFs) of virtual potential temperature (θυ) and water-vapor mixing ratio (r), as well as the mean vertical profiles of θυ, to predict the amount and size distribution of boundary layer cloud cover. This model considers the diversity of air parcels over a heterogeneous surface, and recognizes that some parcels rise above their lifting condensation level to become cumulus, while other parcels might rise as noncloud updrafts. This model has several unique features: 1) cloud cover is determined from the boundary layer JPDF of θυ versus r, 2) clear and cloudy thermals are allowed to coexist at the same altitude, and 3) a range of cloud-base heights, cloud-top heights, and cloud thicknesses are predicted within any one cloud field, as observed. Using data from Boundary Layer Experiment 1996 and a model intercomparsion study using large eddy simulation (LES) based on Barbados Oceanographic and Meteorological Experiment (BOMEX), it is shown that the CuP model does a good job predicting cloud-base height and cloud-top height. The model also shows promise in predicting cloud cover, and is found to give better cloud-cover estimates than three other cumulus parameterizations: one based on relative humidity, a statistical scheme based on the saturation deficit, and a slab model.

scholarly journals RADIANT COOLING EFFECT OF CEILING SLIT CAPABLE OF BOTH DAYLIGHT HARVESTING AND SOLAR HEAT REMOVAL

2021 ◽  
Vol 86 (787) ◽  
pp. 788-796
Author(s):  
Kan SHINDO ◽  
Jun SHINODA ◽  
Ken IKAI ◽  
Takeshi TAKENAKA ◽  
Shuichi TAMURA ◽  
...  
Keyword(s):  
Heat Removal ◽  
Cooling Effect ◽  
Solar Heat ◽  
Radiant Cooling ◽  
Daylight Harvesting

scholarly journals Analysis of an algorithm catching elephants on the Internet

2008 ◽  
Vol DMTCS Proceedings vol. AI,... (Proceedings) ◽  
Author(s):  
Yousra Chabchoub ◽  
Christine Fricker ◽  
Frédéric Meunier ◽  
Danielle Tibi
Keyword(s):  
Asymptotic Behavior ◽  
Markov Chain ◽  
Stochastic Model ◽  
Limit Theorems ◽  
Bloom Filter ◽  
Simplified Model ◽  
The Internet ◽  
Huge Amount ◽  
International Audience ◽  
On Line

International audience The paper deals with the problem of catching the elephants in the Internet traffic. The aim is to investigate an algorithm proposed by Azzana based on a multistage Bloom filter, with a refreshment mechanism (called $\textit{shift}$ in the present paper), able to treat on-line a huge amount of flows with high traffic variations. An analysis of a simplified model estimates the number of false positives. Limit theorems for the Markov chain that describes the algorithm for large filters are rigorously obtained. The asymptotic behavior of the stochastic model is here deterministic. The limit has a nice formulation in terms of a $M/G/1/C$ queue, which is analytically tractable and which allows to tune the algorithm optimally.

scholarly journals On the role of non-electrified clouds in the Global Electric Circuit

2014 ◽  
Vol 14 (7) ◽  
pp. 9815-9847 ◽  
Author(s):  
A. J. G. Baumgaertner ◽  
G. M. Lucas ◽  
J. P. Thayer ◽  
S. A. Mallios
Keyword(s):  
Cloud Cover ◽  
Electric Circuit ◽  
Time Averaging ◽  
Global Electric Circuit ◽  
Fair Weather ◽  
Cloud Data ◽  
Limited Mobility ◽  
Current Divergence ◽  
High Clouds

Abstract. Non-electrified clouds in the fair-weather part of the Global Electric Circuit (GEC) reduce conductivity because of the limited mobility of charge due to attachment to cloud water droplets, effectively leading to a loss of ions. A high-resolution GEC model, which numerically solves the Poisson equation, is used to show that in the fair-weather region currents partially flow around non-electrified clouds, with current divergence above the cloud, and convergence below the cloud. An analysis of this effect is presented for various types of non-electrified clouds, i.e. for different altitude extents, and for different horizontal dimensions, finding that the effect is most pronounced for high clouds with a diameter below 100 km. Based on these results, a method to calculate column and global resistance is developed that can account for all cloud sizes and altitudes. The CESM1(WACCM) Earth System Model as well as ISCCP cloud data are used to calculate the effect of this phenomenon on global resistance. From CESM1(WACCM), it is found that when including non-electrified clouds in the fair-weather estimate of resistance the global resistance increases by up to 73%, depending on the parameters used. Using ISCCP cloud cover leads to an even larger increase, which is likely to be overestimated because of time-averaging of cloud cover. Neglecting current divergence/convergence around small clouds overestimates global resistance by up to 20%, whereas the method introduced by previous studies underestimates global resistance by up to 40%. For global GEC models, a conductivity parametrization is developed to account for the current divergence/convergence phenomenon around non-electrified clouds. Conductivity simulations from CESM1(WACCM) using this parametrization are presented.

scholarly journals Multiyear Summertime Observations of Daytime Fair-Weather Cumuli at the ARM Southern Great Plains Facility

2013 ◽  
Vol 26 (24) ◽  
pp. 10031-10050 ◽  
Author(s):  
Arunchandra S. Chandra ◽  
Pavlos Kollias ◽  
Bruce A. Albrecht
Keyword(s):  
Great Plains ◽  
Vertical Velocity ◽  
Fair Weather ◽  
Cumulus Clouds ◽  
Cloud Droplets ◽  
Geometrical Properties ◽  
Southern Great Plains ◽  
Aspect Ratios ◽  
Velocity Statistics ◽  
Atmospheric Radiation Measurement

Abstract A long data record (14 yr) of ground-based observations at the Atmospheric Radiation Measurement Program (ARM) Southern Great Plains (SGP) site is analyzed to document the macroscopic and dynamical properties of daytime fair-weather cumulus clouds during summer months. First, a fuzzy logic–based algorithm is developed to eliminate insect radar echoes in the boundary layer that hinder the ability to develop representative cloud statistics. The refined dataset is used to document the daytime composites of fair-weather cumulus clouds properties. Doppler velocities are processed for lower reflectivity thresholds that contain small cloud droplets having insignificant terminal velocities; thus, Doppler velocities are used as tracers of air motion. The algorithm is implemented to process the entire 14-yr dataset of cloud radar vertical velocity data. Composite diurnal variations of the cloud vertical velocity statistics, surface parameters, and profiles of updraft and downdraft fractions, bulk velocity of updrafts and downdrafts, and updraft and downdraft mass flux are calculated. Statistics on the cloud geometrical properties such as cloud thickness, cloud chord length, cloud spacing, and aspect ratios are calculated on the cloud scale. The present dataset provides a unique insight into the daytime evolution and statistical description of the turbulent structure inside fair-weather cumuli over land.

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