Convective available potential energy

About: Convective available potential energy is a research topic. Over the lifetime, 936 publications have been published within this topic receiving 43773 citations. The topic is also known as: CAPE.

Eight Kinds of Strong Convective Weather Situations and Related Cloud-Type Characteristics in Jiangxi

Abstract: By means of 11 year(1999-2009) data,such as infrared cloud image,synoptic chart,lightning and ground dangerous telegram,aiming at the 62 processes of strong convective weathers in Jiangxi,on the basis of analysis of large-scale circulation background when convective weather happens,the features of typical clouds from occurrence and development of mesoscale convective cloud band which triggers convective weather were abstracted.It showed that eight types of cloud features are typical cloud patterns forming convective weather in Jiangxi,which include the strong convective cloud type in the edge of subtropical high,the strong convective cloud type in tail of baroclinic disturbance cloud system,MCS in a ground inverted trough,easterly wave(inverted trough of tropical depression),the strong convective cloud band ahead of cold front,MCC ahead of cold front,the strong convective cloud type behind an upper-trough, tropical cyclone and its peripheral cloud type of squall line.The eight kinds of cloud-based features are closely related to the strength and relative position of affected systems such as low trough,shear,cold air, east wind wave and tropical cyclone,upper-air jet and others.The strong convective cloud types in tail of baroclinic disturbance cloud system,the strong convective cloud band ahead of cold front,and MCC ahead of cold front are often related to stronger lower air activities.When 500 hPa trough's meridional degree is large,and low-level warm advection in front of the trough is obvious,baroclinic disturbance clouds are prone to occur,a convective weather easily occurs at its tail.On the other hand,meso-β-scale convective cloud clusters are easy to merge into MCC at abnormal warming center before the front and the unstable center.Rear of the upper trough,edge of the subtropical high and easterly wave are related to the interaction between high-level dry cold air and weather system at mid- and low-latitudes,when high-level negative temperature-variation or water vapor "dark zone" moves closely to the lower-level convergence system, then an MCS develops.When divergent airflow and divergent cirrus clouds occur at the upper level, the MCS near the convergence line of a ground inverted-trough develops strongly.Additionally tropical cyclone and its peripheral cloud type of squall line are closely related to the typhoon.The predictable indicative of the strong convective cloud type in tail of baroclinic disturbance clouds is the best.

Analysis of the initiation and evolution of the strong convective cloud: A case study in SUWAN area

Abstract: Strong convective weather happened in Jiangsu and Anhui Provinces on 5 June 2009. Using the infrared data and visible data of the FY-2C satellite, the evolution and movement of the strong convective cloud can be identified and tracked. The low-level cloud and fog appeared in the morning in Jiangsu provinces made the heating inhomogeneous, which made the atmospheric stratification unstable. When the thunderstorm cloud moved close, Strong convective cloud was triggered. The strong convective cloud in Shandong peninsula at 08 BTC (Beijing Time) moved southwest and developed. After 16 BTC, the arc cloud line of the cloud evolved into deep convective cloud, which merged into another strong convective cloud originating in the middle of Anhui provinces and a stronger convective cloud formed. The area of the stronger convective cloud was even large and its shape was near circular. Then it moved south and dissipated in Zhejiang province at 24 BTC.

The impacts of dust aerosol and convective available potential energy on precipitation vertical structure in southeastern China as seen from multisource observations

Abstract: Abstract. The potential impacts of dust aerosols and atmospheric convective available potential energy (CAPE) on the vertical development of precipitating clouds in southeastern China (20–30∘ N, 110–125∘ E) in June, July, and August from 2000 to 2013 were studied using multisource observations. In southeastern China, heavy-dust conditions are coupled with strong northerly winds that transport air masses containing high concentrations of mineral dust particles, with cold temperatures, and with strong wind shear. This leads to weaker CAPE on dusty days compared with that on pristine days. Based on satellite observations, precipitating drops under dusty conditions grow faster in the middle atmospheric layers (with a temperature of between −5 and +2 ∘C) but slower in the upper and lower layers compared with their pristine counterparts. For a given precipitation top height (PTH), the precipitation rate under dusty conditions is lower in the upper layer but higher in the middle and lower layers. Moreover, the associated latent heating rate released by precipitation in the middle layer is higher. The precipitation top temperature (PTT) shows a fairly good linear relationship with the near-surface rain rate (NSRR): the linear regression slope between the PTT and NSRR is stable under dusty and pristine conditions. However, the PTT0 (the PTT related to rain onset) at the onset of precipitation is highly affected by both the CAPE and aerosol conditions. On pristine days, a stronger CAPE facilitates the vertical development of precipitation and leads to a decrease in PTT0, at a rate of −0.65 ∘C per 100 J kg−1 of CAPE for deep convective precipitation (with a variation of 15 %) and at a rate of −0.41 ∘C per 100 J kg−1 of CAPE for stratiform precipitation (with variation of 12 %). After removing the impacts of CAPE on PTT, dust aerosols led to an increase in PTT0, at a rate of +4.19 ∘C per unit aerosol optical depth (AOD) for deep convective precipitation and at a rate of +0.35 ∘C per unit AOD for stratiform precipitation. This study showed clear evidence that meteorological conditions and aerosol conditions combine to impact the vertical development of precipitation clouds. A quantitative estimation of the sensitivity of PTT to CAPE and dust was also provided.

High-altitude CO2 Clouds On Mars: A View From MEx Observations, The LMD MGCM, And Convective Potential Calculations

Abstract: We will summarize 35 Martian years (Mars Years 27-30) of high-altitude CO2 cloud data from MEx/OMEGA and selected results from Mex/HRSC The 3-year dataset shows that the equatorial cloud activity is centered around the northern summer solstice with a pause at the aphelion, and that their appearance is limited in latitude and longitude HRSC-measured altitudes and cloud speeds provide a rare dataset for comparison with GCMs A comparison with the LMD Mars Global Climate Model shows a good agreement between the model-predicted winds and those observed by the HRSC The LMD-MGCM predicts a strong diurnal variation of temperature at the cloud observation altitudes due to the propagation of the diurnal thermal tide The coldest temperatures in the near-equator cloud altitude range (60-85 km) are observed towards the end of the afternoon, whereas the warmest temperatures are found in the early morning hours Most of the observed clouds are cirrus-type, filamented clouds, but some OMEGA-observed clouds exhibit round, clumpy structures that have been suggested to be of convective origin We asses the plausibility of the hypothesis of mesospheric convection in light of observations and theoretical Convective Available Potential Energy calculations Estimates of convective potential and vertical velocities based on observed cloud properties suggest that the convective clouds could most likely be clusters of smaller scale convective updrafts SPICAM stellar occultations have revealed large supersaturations at high altitudes: to attain the estimated values of CAPE and vertical velocity, most probably only moderate deviations from saturation are required Based on nucleation modeling, such deviations may imply cloud formation via heterogeneous nucleation onto small condensation nuclei

Simulation Study About the Influence of Atmospheric Stratification on Lightning Activities

Abstract: A 2D model about charging and discharging processes in thundercloud is used to simulate three differential atmospheric stratifications resulting in discrepant thunderstorm processes in Beijing region. The dynamic and microphysical processes in thunderstorm and their influence on lightning activities are also discussed.The results indicate that ascending velocity and water vapor are the most important factors to influence lightning activities. At the same time, they affect each other and are together controlled by atmospheric stratification. The magnitude of the ascending velocity determines the intensity of storm and the time when the thunderstorm matured. The thunderstorm with strong updrafts can reach a large height in a short time. Strong persistent updrafts and suffcient water vapor which help to generate more ice phase hydrometeors that directly influence charging and discharging process will prolong the mature stage of the thunderstorm and thereby enhance lightning activities. Though the big density of ice phase hydrometeors can be formed, it is diffcult to sustain a long time in the condition of strong updrafts and scant water vapor. Under the condition of weak updrafts and suffcient water vapor in the whole levels, it is easy to form warm cloud process in which the ice phase process and lightning activities are weak. The favorable stratification conditions for strong lightning activities are the suffcient vapor in the lower atmosphere,moderate humidity in the mid troposphere, big instability energy and some suitable convective inhibition.Through calculating some atmospheric instability parameters, it is indicated that convective instability index smaller than -10 °C (negative means instable), convective available potential energy larger than 1000 J kg-1, convective inhibition larger than 40 J kg-1, the 700-hPa potential equivalent temperature larger than 340 K and the 35%-85% humidity in the mid troposphere (700-400 hPa) are the advantageous conditions for strong lightning activities.