Search Results

You are looking at 1 - 10 of 13,812 items for :

  • Warm fronts x
  • All content x
Clear All
Dustin J. Swales, George S. Young, Todd D. Sikora, Nathaniel S. Winstead, and Hampton N. Shirer

1. Introduction Warm fronts are often considered to be one of the more benign aspects of baroclinic cyclones. Modern satellite remote sensors, however, tell a different story with warm fronts supporting a variety of interesting mesoscale phenomena ( Young et al. 2005 ). Using ocean surface images from satellite-borne synthetic aperture radar (SAR) and a range of other data sources, Young et al. (2005) examined 22 warm fronts, primarily in the Gulf of Alaska. One of the more striking findings

Full access
Catherine M. Naud, Derek J. Posselt, and Susan C. van den Heever

not form enough clouds across cold and warm fronts, partly because of its coarse spatial resolution. Another model tested by Field et al. (2011) was also found to produce less clouds poleward of the low than observed with CloudSat ( Stephens et al. 2002 ). It is unclear whether anomalously large oceanic solar absorption is predominantly due to insufficient storm activity or to deficient representation of cloud processes. A consistent result from the aforementioned studies is the fact that this

Full access
Mirja L. Kemppi and Victoria A. Sinclair

1. Introduction Conceptual models of warm fronts have changed little from what was first conceived by the Norwegian school ( Bjerknes 1919 ; Bjerknes and Solberg 1922 ). Today’s textbooks (e.g., Bluestein 1993 ; Ahrens 1994 ; Wallace and Hobbs 2006 ) present warm fronts as sloping zones that tilt forward over the prefrontal cold air and extend from the surface to the midtroposphere. In such conceptual models (e.g., Ahrens 1994 , chapter 12) the passage of the surface warm front is

Full access
Catherine M. Naud, Derek J. Posselt, and Susan C. van den Heever

1. Introduction The midlatitudes, where most of the world’s population resides, are strongly affected by the passage of extratropical cyclones and their warm and cold fronts, and in particular by the amount of precipitation they might produce (e.g., Stewart et al. 1998 ; Kunkel et al. 2012 ). Insufficient precipitation affects crops and water supply, whereas precipitation extremes can result in havoc and severe loss of life and property. In the context of a warming world, it is still unclear

Full access
Adele L. Igel, Susan C. van den Heever, Catherine M. Naud, Stephen M. Saleeby, and Derek J. Posselt

these indirect effects and feedbacks of aerosols is an ongoing and difficult task, especially since the environment and dynamics of the system itself can alter the response to aerosols ( Matsui et al. 2006 ; Fan et al. 2009 ; Khain 2009 ; Storer et al. 2010 ). Since the mesoscale dynamics of an extratropical cyclone differ greatly between the cold and warm fronts, a detailed study of all of the impacts of aerosols on extratropical cyclones is too extensive for one study; therefore, this paper

Full access
Jiaolan Fu, Fuqing Zhang, and Timothy D. Hewson

1. Introduction Weather occurring well ahead of a surface cold front is typically described as prefrontal or warm-sector weather ( Omoto 1965 ; Nozumi and Arakawa 1968 ). Omoto (1965) indicated that in the United States, to the east of the Rocky Mountains, extensive precipitation zones occur frequently in the warm sectors of cyclones. The lifting mechanism causing the rainfall has been shown to often derive from synoptic-scale disturbances aloft rather than local forcing near the ground

Restricted access
Brian A. Colle, Aaron R. Naeger, and Andrew Molthan

1. Introduction a. Background Warm fronts and their associated precipitation areas have been studied since the Norwegian School ( Bjerknes 1919 ; Bjerknes and Solberg 1922 ), but they have generally received less attention than cold fronts. During the 1970s and 1980s, observational studies used radar, aircraft, and conventional surface and upper-air data to document some of the surface frontal wind, temperature, and precipitation structures. Houze et al. (1976) found a tendency for

Full access
Peter R. Bannon

15JUNE 1984 NOTES AND CORRESPONDENCE 2021NOTES AND CORRESPONDENCEEffects of Stratification on Surface Frontogenesis: Warm and Cold Fronts PETER R. BANNON Department of the Geophysical Sciences, The University of Chicago, Chicago, 1L 60637 9 December 1983 and 9 April 1984 ABSTRACT The role of the ambient stratification in ~migeostrophic surface

Full access
Juan A. Crespo, Derek J. Posselt, Catherine M. Naud, and Charles Bussy-Virat

majority of the precipitation observed in the planet’s temperate zones ( Heideman and Fritsch 1988 ; Hawcroft et al. 2012 ). Most of the water vapor that is converted to clouds and precipitation within extratropical fronts and cyclones is transported poleward by the warm conveyor belt (WCB; Harrold 1973 ; Browning et al. 1973 ; Carlson 1980 ; Browning 1986 ; Wernli 1997 ; Catto 2016 ). WCBs typically originate in a moist subtropical marine planetary boundary layer between 20° and 47°N and

Full access
Roger M. Wakimoto and Brian L. Bosart

have been relatively few studies on warm fronts, as noted by Keyser (1986) , leading to a less complete conceptualization of its structure. The dearth of observational analyses on the warm front is, in part, owing to the weakness of the associated surface discontinuity and general absence of severe convective activity. The warm front can often be difficult to locate on a surface map and is of limited horizontal extent compared to the cold front (e.g., Hoskins and West 1979 ; Bluestein 1993

Full access