Idealised simulations of cyclones with robust symmetrically-unstable sting jets

Idealised simulations of Shapiro-Keyser cyclones developing a sting jet (SJ) are presented. Thanks to an improved and accurate implementation of thermal wind balance in the initial state, it has been possible to use more realistic environments than in previous idealised studies. As a consequence, this study provides further insight in SJ evolution and dynamics and explores SJ robustness to different environmental conditions, assessed via a wide range of sensitivity experiments. The control simulation contains a cyclone that fits the Shapiro-Keyser conceptual model and develops a SJ whose dynamics are associated with the evolution of mesoscale instabilities along the airstream, including symmetric instability (SI). The SJ undergoes a strong descent while leaving the cloud-head banded tip and markedly accelerating towards the frontal-fracture region, revealed as an area of buckling of the already-sloped moist isentropes. Dry instabilities, generated by vorticity tilting via slantwise frontal motions in the cloud head, exist in similar proportions to moist instabilities at the start of the SJ descent and are then released along the SJ. The observed evolution supports the role of SI in the airstream’s dynamics proposed in a conceptual model outlined in a previous study. Sensitivity experiments illustrate that the SJ is a robust feature of intense Shapiro-Keyser cyclones, highlighting a range of different environmental conditions in which SI contributes to the evolution of this airstream, conditional on the model having adequate resolution. The results reveal that several environmental factors can modulate the strength of the SJ. However, a positive relationship between the strength of the SJ, both in terms of peak speed and amount of descent, and the amount of instability occurring along it can still be identified. In summary, the idealised simulations presented in this study show the robustness of SJ occurrence in intense Shapiro-Keyser cyclones and support and clarify the role of dry instabilities in SJ dynamics

Chionactis occipitalis

Number of Pages: 12Integrative BiologyGeological Science

Zika Virus: Can Artificial Contraception Be Condoned?

As the Zika virus pandemic continues to bring worry and fear to health officials and medical scientists, Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) have recommended that residents of the Zika-infected countries, e.g., Brazil, and those who have traveled to the area should delay having babies which may involve artificial contraceptive, particularly condom. This preventive policy, however, is seemingly at odds with the Roman Catholic Church’s position on the contraceptive. As least since the promulgation of Paul VI’s 1968 encyclical, Humanae Vitae, the Church has explicitly condemned artificial birth control as intrinsic evil. However, the current pontiff, Pope Francis, during his recent visit to Latin America, remarked that the use of artificial contraception may not be in contradiction to the teaching of Humanae Vitae while drawing a parallel between the current Zika Crisis and the 1960’s Belgian Congo Nun Controversy. The pope mentioned that the traditional ethical principle of the lesser of two evils may be the doctrine that justified the exceptions. The authors of this paper attempt to expand the theological rationale of the pope’s suggestion. In so doing, the authors rely on casuistical reasoning as an analytic tool that compares the Belgian Congo Nun case and the given Zika case, and suggest that the former is highly similar to, if not the same as, the latter in terms of normative moral feature. That is, in both cases the use of artificial contraception is theologically justified in reference to the criteria that the doctrine of the lesser of two evils requires. The authors wish that the paper would provide a solid theological-ethical ground based on which condom-use as the most immediate and effective preventive measure can be recommended in numerous Catholic hospitals as well as among Catholic communities in the world, particularly the most Zika-affected and largest Catholic community in the world, Brazil – 123 million present Brazilian citizens are reported to be Roman Catholic

Chionactis palarostris

Number of Pages: 5Integrative BiologyGeological Science

Sting jets in extratropical cyclones: a review

This paper reviews the current state of knowledge of sting jets in extratropical cyclones. Sting jets were formally identified in 2004 by the pioneering work of Keith Browning. Reviewing this and subsequent studies, we define the sting jet as a coherent air flow that descends from mid-levels inside the cloud head into the frontal-fracture region of a Shapiro-Keyser cyclone over a period of a few hours leading to a distinct region of near-surface stronger winds. It therefore lies above the cold conveyor belt during some stage its life, but, at least in some cases, descends to reach the top of boundary layer ahead of the cold conveyor belt. It is not attributed to a specific mechanism in this definition. We conclude that it is likely that a continuum of sting jet descent and speed-up mechanisms exists. At one extreme is balanced descent partly associated with frontolysis in the frontal-fracture region. More horizontally small-scale and stronger frontolytic descent may occur associated with weak stability to slantwise convective downdraughts. Instability to slantwise convective downdraughts may occur in some systems, leading to multiple slantwise convective downdraughts associated with the release of conditional symmetric instability and even, possibly, symmetric instability. The global climatology of sting jets and the interaction between the atmospheric boundary layer and sting jets are revealed as specific areas where more research is needed. Finally, we describe eight myths and misunderstandings that exist in the current literature with the aim of guiding future research into the sting jet phenomenon