Weather – July 2009, Vol. 64, No. 7 180 ENSO and the Ashes series References Jones DA, Trewin BC. 2000. On the rela- tionships between the El-Niño Southern Oscillation and Australian land surface tem- perature. Int. J. Climatology 20: 697–719. McBride JL, Nichols N. 1983. Seasonal relationships between Australian rain- fall and the Southern Oscillation, Mon. Weather. Rev. 111: 1998–2004. Timbal B, Power S, Colman R, Viviand J and Lirola S. 2002. Does soil moisture Correspondence to: Manoj Joshi, Walker Institute for Climate Systems Research, Department of Meteorology, University of Reading, Earley Gate, Reading, RG6 6BB, UK Email: m.m.joshi@reading.ac.uk © Royal Meteorological Society, 2009 DOI: 10.1002/wea.403 influence climate variability and pre- dictability over Australia? J. Climate 15: 1230–1238. Westra S, Sharma A. 2006. Dominant modes of interannual variability in Australian rainfall analyzed using wave- lets. J. Geophys. Res. 111, D05102. Xie P, Arkin PA. 1997. A 17-year monthly analysis based on gauge observa- tions, satellite estimate and numerical model outputs. Bull. Am. Met. Soc. 78: 2539–2559. The photographs show small-scale atmos- pheric processes resulting in dust uplift into the atmosphere. Such dust is an important component of the climate system and the radiative impact of airborne desert dust can affect regional dynamics (Tompkins et al., 2005). Figures 1(a) and (b) show dust uplift in cold pool outflows from small precipitating convective clouds in arid regions of the USA and Niger. Although virgae can be seen in Figure 1(a), precipitation does not appear to reach the ground, but dust is still uplifted. A few minutes prior to the photo, a rainbow was visible with the same cloud. In Figure 1(b), the cloud was the first of a number of cumulus congestus and cumulonimbus clouds, which generated precipitation and outflows that resulted in visible dust uplift. The dusty cold-pool outflow is seen below the right-hand tower of the congestus cloud, and is probably contributing to generation of this tower. The uplift of dust by cold-pool outflows from deep convective systems is a well- known phenomenon, with the earliest published scientific discussion of these features, which the authors are aware of, focusing on the Sudan (Sutton, 1925). There they are referred to as ‘haboobs’ (from the Arabic habb, meaning ‘strong wind’) and this term is now used globally to refer to these features. The evaporation of precipitation from convective clouds results in a cold downdraught, and the resultant cold-pool outflow propagates along the land surface as a density current. Large haboobs can often be seen in satellite imagery, particularly in West Africa, where outflows from mesoscale convective systems (MCSs) can travel over Figure 1. Two photographs showing cold pool outflows from precipitating convective clouds resulting in visible dust uplift. (a) Searles Valley near Death Valley in California, USA, 16 September 2008; (b) West African Sahel near Niamey, Niger, during monsoon onset, 26 June 2007. Figure 1(b) was taken during the GERBILS (GERB Intercomparsion of Longwave and Shortwave radiation) field campaign, aimed at understanding the differences between modelled and observed radiation in West Africa, which may be largely due to the airborne dust (Haywood et al., 2005). (© C. M. Grams.) (a) (b) Photographs of dust uplift from small-scale atmospheric features