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- Author or Editor: Joseph H. Golden x
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Abstract
The high formation frequency and previously documented life cycle of Florida Keys' waterspouts result from energy and angular momentum cascades through five scales of atmospheric motion, namely the funnel, spiral, cumulus, cloud-line and synoptic scales.
The funnel scale appears to be the most complicated in that pronounced horizontal and vertical flow asymmetries in the spray vortex and funnel-cloud walls have been quantitatively analyzed. Waterspouts are apparently a two-cell type of radial vertical circulation.
The spiral scale of motion is first defined by sea surface spiral patterns during stage 2 of the waterspout life cycle. The spiral scale is important because it marks the primary waterspout growth phase and gives the first visual evidence of boundary layer rotation and inflow.
The single-cumulus scale is important in providing updrafts and shower outflow for concentrating larger-scale vorticity.
Motions on the cloud-line scale are perhaps most crucial for waterspout formation. Less than 5% of all 1969–70 waterspouts were spawned by isolated cumulus clouds. Individual shower cells in a cloud-line protect one another from dilution by entrainment, and shower outflows interact to further concentrate the weak large-scale positive vorticity. In some cases the shear across shower-induced wind-shift lines may be the vorticity source for waterspouts.
Finally, the fifth interacting scale of motion, the synoptic scale, is shown to exert a controlling influence on convective cloud-line developments in the Lower Keys.
Abstract
The high formation frequency and previously documented life cycle of Florida Keys' waterspouts result from energy and angular momentum cascades through five scales of atmospheric motion, namely the funnel, spiral, cumulus, cloud-line and synoptic scales.
The funnel scale appears to be the most complicated in that pronounced horizontal and vertical flow asymmetries in the spray vortex and funnel-cloud walls have been quantitatively analyzed. Waterspouts are apparently a two-cell type of radial vertical circulation.
The spiral scale of motion is first defined by sea surface spiral patterns during stage 2 of the waterspout life cycle. The spiral scale is important because it marks the primary waterspout growth phase and gives the first visual evidence of boundary layer rotation and inflow.
The single-cumulus scale is important in providing updrafts and shower outflow for concentrating larger-scale vorticity.
Motions on the cloud-line scale are perhaps most crucial for waterspout formation. Less than 5% of all 1969–70 waterspouts were spawned by isolated cumulus clouds. Individual shower cells in a cloud-line protect one another from dilution by entrainment, and shower outflows interact to further concentrate the weak large-scale positive vorticity. In some cases the shear across shower-induced wind-shift lines may be the vorticity source for waterspouts.
Finally, the fifth interacting scale of motion, the synoptic scale, is shown to exert a controlling influence on convective cloud-line developments in the Lower Keys.
Abstract
Detailed, multi-faceted analyses show that waterspouts have a characteristic life cycle consisting of five discrete but overlapping stages: 1) the dark spot, a prominent light-colored disc on the sea surface surrounded by a dark patch, diffuse on its outer edges, which represents a complete vortex column from cloud base to sea surface; 2) the spiral pattern, the primary growth phase of the waterspout, characterized by alternating dark- and light-colored surface bands around the dark spot; 3) the spray ring (incipient spray vortex), concentrated around the dark spot, with a lengthening funnel above; 4) the mature waterspout (spray vortex), the stage of maximum overall organization and intensity; and 5) the decay stage, when waterspout dissipation (often abrupt) is initiated by cool downdrafts from a nearby developing rain shower.
Abstract
Detailed, multi-faceted analyses show that waterspouts have a characteristic life cycle consisting of five discrete but overlapping stages: 1) the dark spot, a prominent light-colored disc on the sea surface surrounded by a dark patch, diffuse on its outer edges, which represents a complete vortex column from cloud base to sea surface; 2) the spiral pattern, the primary growth phase of the waterspout, characterized by alternating dark- and light-colored surface bands around the dark spot; 3) the spray ring (incipient spray vortex), concentrated around the dark spot, with a lengthening funnel above; 4) the mature waterspout (spray vortex), the stage of maximum overall organization and intensity; and 5) the decay stage, when waterspout dissipation (often abrupt) is initiated by cool downdrafts from a nearby developing rain shower.
Abstract
No abstract available.
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No abstract available.
Abstract
Ship reports dating back to the 1880's and Storm Data (1959–73) are used to assess the threat posed by waterspouts to existing and proposed floating offshore nuclear power plants along the U.S. East and Gulf Coasts. In particular, it is found that the primary warm axis of the Gulf Stream and large coastal bays and inland waterways are favored regions of waterspout occurrence. A list of the ten most active coastal regions, in terms of reported waterspouts per unit area, is synthesized. It is shown that after the Florida Keys, the most prolific waterspout region is the entire southeast Florida Coast (Stuart to Homestead). Tampa Bay has had the greatest number of damaging waterspouts.
Abstract
Ship reports dating back to the 1880's and Storm Data (1959–73) are used to assess the threat posed by waterspouts to existing and proposed floating offshore nuclear power plants along the U.S. East and Gulf Coasts. In particular, it is found that the primary warm axis of the Gulf Stream and large coastal bays and inland waterways are favored regions of waterspout occurrence. A list of the ten most active coastal regions, in terms of reported waterspouts per unit area, is synthesized. It is shown that after the Florida Keys, the most prolific waterspout region is the entire southeast Florida Coast (Stuart to Homestead). Tampa Bay has had the greatest number of damaging waterspouts.
Abstract
An analysis of the Lower Matecumbe Key 1967 waterspout data is presented. It was found that the flow field synthesized across the spray vortex of the second, larger waterspout is closely approximated by a Rankine-combined vortex with solid rotation over a circle 24 m in diameter. Five major tornadoes were documented in the Greater Miami area during 1968, and this anomalous number is ascribed to the development of strong localized zones of convergence on the mesoscale along or slightly inland from the southeast coast where the prevailing southwesterly tropospheric flow interacts with the sea breeze induced by the Florida Peninsula. On the other hand, the large number of waterspouts documented in the Lower Keys during the summer of 1968 were spawned by cumulus congestus cloud lines embedded in a very warm undisturbed trade-wind flow.
Extensive documentation of close-range observations was obtained for an unusually large “tornadic waterspout” that passed through a crowded coastal marina in Miami. Evidence concerning the formation process, flow kinematics, and the problem of a “flying houseboat” are presented.
Abstract
An analysis of the Lower Matecumbe Key 1967 waterspout data is presented. It was found that the flow field synthesized across the spray vortex of the second, larger waterspout is closely approximated by a Rankine-combined vortex with solid rotation over a circle 24 m in diameter. Five major tornadoes were documented in the Greater Miami area during 1968, and this anomalous number is ascribed to the development of strong localized zones of convergence on the mesoscale along or slightly inland from the southeast coast where the prevailing southwesterly tropospheric flow interacts with the sea breeze induced by the Florida Peninsula. On the other hand, the large number of waterspouts documented in the Lower Keys during the summer of 1968 were spawned by cumulus congestus cloud lines embedded in a very warm undisturbed trade-wind flow.
Extensive documentation of close-range observations was obtained for an unusually large “tornadic waterspout” that passed through a crowded coastal marina in Miami. Evidence concerning the formation process, flow kinematics, and the problem of a “flying houseboat” are presented.
Abstract
No abstract available.
Abstract
No abstract available.
Abstract
A major tornado struck the small farming community of Union City, Okla., on 24 May 1973. It was on the ground 26 min, attaining a maximum width (at cloud base) of nearly 600 m. Even though the funnel narrowed toward the ground, the width of the damage path consistently equalled funnel width at cloud base. The tornado life cycle consisted of four distinct parts: organizing stage (visible funnel intermittently touching ground with continuous damage path), mature stage (tornado at largest size), shrinking stage (entire funnel decreasing to thin column), and decaying stage (fragmented, contorted funnel). Even in its final stages, the tornado retained its destructiveness.
The tornado life cycle resembles, in many respects, that typical of Florida Keys waterspouts. Both commence with surface evidence of vortex existence before a visible funnel cloud has descended a significant distance toward the surface. Approaching the mature stage, the tornado and waterspout exhibit spiral inflow characteristics with a distinct boundary between warm, moist air and cool, dry air. The cooler air mass from a nearby precipitation area apparently cuts off flow of warm, moist air into the tornado's circulation, leading to vortex decay. The visible funnel becomes thin, increasingly tilted and distorted as it dissipates. Major differences between the tornado and waterspout appear to be vortex and parent cloud scales and, to a lesser extent, vortex lifetimes and intensities. Both vortices may evolve rapidly through their respective life cycles without evolving through every stage.
Abstract
A major tornado struck the small farming community of Union City, Okla., on 24 May 1973. It was on the ground 26 min, attaining a maximum width (at cloud base) of nearly 600 m. Even though the funnel narrowed toward the ground, the width of the damage path consistently equalled funnel width at cloud base. The tornado life cycle consisted of four distinct parts: organizing stage (visible funnel intermittently touching ground with continuous damage path), mature stage (tornado at largest size), shrinking stage (entire funnel decreasing to thin column), and decaying stage (fragmented, contorted funnel). Even in its final stages, the tornado retained its destructiveness.
The tornado life cycle resembles, in many respects, that typical of Florida Keys waterspouts. Both commence with surface evidence of vortex existence before a visible funnel cloud has descended a significant distance toward the surface. Approaching the mature stage, the tornado and waterspout exhibit spiral inflow characteristics with a distinct boundary between warm, moist air and cool, dry air. The cooler air mass from a nearby precipitation area apparently cuts off flow of warm, moist air into the tornado's circulation, leading to vortex decay. The visible funnel becomes thin, increasingly tilted and distorted as it dissipates. Major differences between the tornado and waterspout appear to be vortex and parent cloud scales and, to a lesser extent, vortex lifetimes and intensities. Both vortices may evolve rapidly through their respective life cycles without evolving through every stage.
Abstract
The NSSL Tornado-Intercept Project team intercepted and photographed an intense tornado that struck Union City, Okla., on 24 May 1973. The life cycle of the tornado was photographically documented. Photo-grammetric data permitted velocity measurements from debris and cloud-tag motion. When the tornado was at its maximum size and intensity 2 km west of Union City, maximum measured horizontal velocities in the debris cloud were 60–80 m s−1 at 90 m elevation and a radius of about 200 m. At the same time, cloud tags rotating around the upper periphery of the tornado funnel had horizontal velocities up to 30–45 m s−1 at radii of 400–700 m from the tornado's axis. A few representative calculations of upward velocities yield 13–30 m s−1 in the debris cloud below 100 m elevation and 10–15 m s−1 in a “feeder” band of cloud tags which spiraled into the tornado near cloud base from the northeast. During the tornado's decay stage, tangential velocities of particles orbiting the funnel ranged from 40 to 65 m s−1, at radii generally between 25 and 50 m. The tornado's debris-cloud circulation decreased from 6.O × 104 to 1.6 × 104 m2 s−1 between the mature and decay stages. Finally, the tornado's apparent flow structure, as inferred from debris and cloud-tag trajectories, was strongly asymmetric in both rotational and vertical flow components.
Abstract
The NSSL Tornado-Intercept Project team intercepted and photographed an intense tornado that struck Union City, Okla., on 24 May 1973. The life cycle of the tornado was photographically documented. Photo-grammetric data permitted velocity measurements from debris and cloud-tag motion. When the tornado was at its maximum size and intensity 2 km west of Union City, maximum measured horizontal velocities in the debris cloud were 60–80 m s−1 at 90 m elevation and a radius of about 200 m. At the same time, cloud tags rotating around the upper periphery of the tornado funnel had horizontal velocities up to 30–45 m s−1 at radii of 400–700 m from the tornado's axis. A few representative calculations of upward velocities yield 13–30 m s−1 in the debris cloud below 100 m elevation and 10–15 m s−1 in a “feeder” band of cloud tags which spiraled into the tornado near cloud base from the northeast. During the tornado's decay stage, tangential velocities of particles orbiting the funnel ranged from 40 to 65 m s−1, at radii generally between 25 and 50 m. The tornado's debris-cloud circulation decreased from 6.O × 104 to 1.6 × 104 m2 s−1 between the mature and decay stages. Finally, the tornado's apparent flow structure, as inferred from debris and cloud-tag trajectories, was strongly asymmetric in both rotational and vertical flow components.
Abstract
On 14 August 1977, there was a mini-outbreak of three tornadoes about 40 km cut of Denver, Colorado. There were no significant synoptic-scale disturbances affecting Colorado on that day. Mesoscale analysis is used to establish several smaller scale systems that influenced storm development. The most notable feature of the mesoscale band of parent thunderstorms was the active growth along their northwest flank, in spite of cell movement toward the east. On the convective scale, the situation can be described as discrete propagation of multi-cell storms by new cell development on the left rear flank. Two of the three tornadoes were documented photographically, and post-analysis shows that they were of large size and long duration, but slow moving. Structural features of the largest tornado are analyzed in different portions of the life cycle, and compared with other cases in the literature. This tornado moved on a track curving toward the north-northwest, remaining at least 5–10 km distant from any significant precipitation. A dust band believed to represent an inflow jet was observed, which was in a different quadrant from similar features in other cases. Aspects of the tornadoes which could cause public confusion are noted, such as the disproportionately short condensation funnel from high-based cumulus clouds.
Abstract
On 14 August 1977, there was a mini-outbreak of three tornadoes about 40 km cut of Denver, Colorado. There were no significant synoptic-scale disturbances affecting Colorado on that day. Mesoscale analysis is used to establish several smaller scale systems that influenced storm development. The most notable feature of the mesoscale band of parent thunderstorms was the active growth along their northwest flank, in spite of cell movement toward the east. On the convective scale, the situation can be described as discrete propagation of multi-cell storms by new cell development on the left rear flank. Two of the three tornadoes were documented photographically, and post-analysis shows that they were of large size and long duration, but slow moving. Structural features of the largest tornado are analyzed in different portions of the life cycle, and compared with other cases in the literature. This tornado moved on a track curving toward the north-northwest, remaining at least 5–10 km distant from any significant precipitation. A dust band believed to represent an inflow jet was observed, which was in a different quadrant from similar features in other cases. Aspects of the tornadoes which could cause public confusion are noted, such as the disproportionately short condensation funnel from high-based cumulus clouds.
