Compressibility and windspeed limits in tornadoes

Tweeting and tornadoes

Social Media and micro-blogging is being used during crisis events to provide live up-to-date information as events evolve (before, during and after). Messages are posted by citizens or public officials. To understand the effectiveness of these messages, we examined the content of geo-located Twitter messages (“tweets”) sent during the Moore, Oklahoma tornado of May 20, 2013 (+/-1day) to explor...

Forecasting Tornadoes in Georgia

Some climatological data on the seasonal, diurnal, and geographical distribut>iorl of tornadoes in Georgia are presented, and the tornado "season" is defined as occurring from February through April. Twelve different storms producing t,ornadoes during one or more 12-hour forecast periods are studied for synoptic similarities. A mean tornado sounding and a 700-mb. composite chart, taken from dat...

Precipitation, the Rear Flank Downdraft, and Tornadoes

1. INTRODUCTION Because of the apparent importance of dynamic and thermodynamic properties of RFDs to tornadogenesis, these are studied for a variety of prescribed environments using a 1.5-dimension downdraft model. The spatial dimensionality of this model is purposely less than three so as to simplify analyses and to focus on vertical processes, which are thought to be of primary importance. M...

Generalized Covering Groups and Direct Limits

Limits in modified categories of interest

‎We firstly prove the completeness of the category of crossed modules in a modified category of interest‎. ‎Afterwards‎, ‎we define pullback crossed modules and pullback cat objects that are both obtained by pullback diagrams with extra structures on certain arrows‎. ‎These constructions unify many corresponding results for the cases of groups‎, ‎commutative algebras and can also be adapted to ...