Tropical cyclones over the Arabian Sea in the pre-monsoon season (May–June) have intensified since 1997 (ref. 1, Fig. 1a) owing to significant reductions in storm-ambient vertical wind shear (VWS) in the troposphere; these reductions have decreased on average by about 3m s from the pre-1997 epoch (1979–1997) to the recent epoch (1998–2010). The authors attribute the reduction of premonsoon VWS ...

An analysis is made of the generation, advection, and dissipation processes of the cirrus canopy in tropical storms with particular emphasis on the formation of sharp edges. Although subsidence and accompanying evaporation may be factors, this formation is closely tied with the wind flow pattern near the edges. The stronger the radial wind velocity in the vicinity of the edges, the greater is t...

Introduction Conclusions References

Article history: Received 2 January 2011 Received in revised form 23 May 2011 Accepted 1 July 2011 Available online 12 July 2011

The variability of North Atlantic tropical storm and hurricane tracks, and its relationship to climate variability, is explored. Tracks from the North Atlantic hurricane database for the period 1950–2007 are objectively separated into four groups using a cluster technique that has been previously applied to tropical cyclones in other ocean basins. The four clusters form zonal and meridional sep...

Article history: Received 30 August 2012 Received in revised form 29 January 2013 Accepted 25 February 2013 Available online xxxx

The severity of a tropical cyclone (TC) is often summarized by its lifetime maximum intensity (LMI), and the climatological LMI distribution is a fundamental feature of the climate system. The distinctive bimodality of the LMI distribution means that major storms (LMI >96 kt) are not very rare compared with less intense storms. Rapid intensification (RI) is the dramatic strengthening of a TC in...

Although migration is a widespread and taxonomically diverse behaviour, the ecological factors shaping migratory behaviour are poorly understood. Like other montane taxa, many birds migrate along elevational gradients in the tropics. Forty years ago, Alexander Skutch postulated that severe storms could drive birds to migrate downhill. Here, we articulate a novel mechanism that could link storms...