purpose estimating wind chill index as one of the indexes effective in body comfort, specifically for athletes and tourists interested in winter sports. methods meteorology data including temperature and the percentage of relative humidity of 6 synoptic stations of chaharmahal-bakhtiyrai province, iran from 1990 to 2007 were extracted from iranian meteorology site. in order to calculate the val...

There has been intense debate about the causes of the 1997–1998 El Niño. One side sees the obvious intense westerly wind events as the main cause for the exceptional heating in summer 1997, the other emphasizes slower oceanic processes. We present a quantitative analysis of all factors contributing to the onset of this El Niño. At six months’ lead time the initial state contributes about 40% of...

The National Centers for Environmental Prediction–National Center for Atmospheric Research (NCEP–NCAR) reanalysis is used to estimate time trends of, and analyze the relationships among, six indices of cyclone activity or forcing for the winters of 1949–99, over the region 208–708N. The indices are Eady growth rate and temperature variance, both at 500 hPa; surface meridional temperature gradie...

[1] A large-eddy simulation model is used to examine the impact of the intense cross-inversion wind shear on the stratocumulus cloud structure. The wind shear enhanced entrainment mixing effectively reduces the cloud water and thickens the inversion layer. It leads to a reduction of the turbulence kinetic energy (TKE) production in the cloud layer due to the weakened cloud-top radiative cooling...

In the past most diagnostic studies of frontal cyclone development have been carried out through use of quasigeostrophic models. In this paper we present the results of vertical motions obtained from a 5-level general balance model. Nongeostrophic effects such as deformation and beta term of the balance equations, divergence, vertical advection, and the twisting term of the complete vorticity e...

Spreading fires are noisy (and potentially chaotic) systems in which transitions in dynamics are notoriously difficult to predict. As flames move through spatially heterogeneous environments, sudden shifts in temperature, wind, or topography can generate combustion instabilities, or trigger self-stabilizing feedback loops, that dramatically amplify the intensities and rates with which fires pro...

Volcanic eruptions can generate widespread deposits of ash that are subsequently subjected to erosive forces which causes detrimental effects on ecosystems. We measured wind erosion of the freshly deposited Eyjafjallajökull ash at a field site the first summer after the 2010 eruption. Over 30 wind erosion events occurred (June-October) at wind speeds > 10 m s(-1) in each storm with gusts up to ...

Pulsars are heavy, compact, rapidly rotating stars, surrounded by intense electric and magnetic fields. Plasma near the pulsar surface is accelerated away from the pulsar by the fields to form a pulsar wind. The accepted, steady-state pulsar wind model does not correctly predict the observed energy transport in the wind. The wind contains both an electromagnetic and a kinetic energy component. ...