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- Author or Editor: HAROLD W. BAYNTON x
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Abstract
Four resistance thermometers which are installed on the WJBK-TV tower in Detroit provide continuous records of the temperatures at heights of 20, 300, 600, and 870 ft. From these records, times of formation and burn off of nocturnal inversions have been logged for the period 1 December 1956 to 31 March 1958.
Time of formation, defined as appearance of an inversion between 20 and 300 ft, has been related to time of sunset. When this is done two regimes appear, as follows. During the 5 months, January through May, inversions tend to form about 2 hours after sunset. During the 5 months, July through November, they tend to form at sunset. The months of June and December appear to be transitional months.
Time of burn off, defined as time of disappearance of an inversion from the layer 20 ft to 870 ft, has been related to time of sunrise with the following results. During the interval April through August burn off occurs most frequently about 3 hours after sunrise. During the interval 1 September to 31 March, burn off occurs about 2 hours after sunrise.
Abstract
Four resistance thermometers which are installed on the WJBK-TV tower in Detroit provide continuous records of the temperatures at heights of 20, 300, 600, and 870 ft. From these records, times of formation and burn off of nocturnal inversions have been logged for the period 1 December 1956 to 31 March 1958.
Time of formation, defined as appearance of an inversion between 20 and 300 ft, has been related to time of sunset. When this is done two regimes appear, as follows. During the 5 months, January through May, inversions tend to form about 2 hours after sunset. During the 5 months, July through November, they tend to form at sunset. The months of June and December appear to be transitional months.
Time of burn off, defined as time of disappearance of an inversion from the layer 20 ft to 870 ft, has been related to time of sunrise with the following results. During the interval April through August burn off occurs most frequently about 3 hours after sunrise. During the interval 1 September to 31 March, burn off occurs about 2 hours after sunrise.
It is common practice to compute wind run and mean wind by counting the total number of anemometer rotations in a measured time. The practice assumes that each turn of the rotor signifies the passage of a fixed run of wind, or that the anemometer's performance is expressed by S = bR, where S is wind speed in meters per second, b is a coefficient with units of meters per revolution, and R is the turning rate in revolutions per second. Tests in NCAR's wind tunnel show that, although true helicoid anemometers obey the equation S = bR, all other types of rotational anemometers obey the equation S = a + bR. The significance of errors due to this oversight is discussed.
It is common practice to compute wind run and mean wind by counting the total number of anemometer rotations in a measured time. The practice assumes that each turn of the rotor signifies the passage of a fixed run of wind, or that the anemometer's performance is expressed by S = bR, where S is wind speed in meters per second, b is a coefficient with units of meters per revolution, and R is the turning rate in revolutions per second. Tests in NCAR's wind tunnel show that, although true helicoid anemometers obey the equation S = bR, all other types of rotational anemometers obey the equation S = a + bR. The significance of errors due to this oversight is discussed.
Hurricanes cause sporadic devastation along the Gulf and Atlantic coasts despite intensive research and a warning system that integrates satellite surveillance, aircraft reconnaissance, and a network of coastal radars. Part of the devastation must be attributed to inadequate public preparation and response and part to the limits of weather predictability, but part must be attributed to the use of an outmoded radar system. Although there now exist Doppler radars that provide real-time colored displays of the wind structure in storms, the radars that comprise the last line of defense in the national hurricane warning service provide no wind information.
To support the contention that the coastal network should consist of Doppler radars, this paper develops a scenario in which a hurricane is approaching Galveston. A Doppler radar is imagined to be located at Galveston. The hurricane is assigned an average wind structure from which the field of wind components directed towards the radar is computed. After color coding the entire wind field, the corresponding color-coded radar display is obtained for a plausible distribution of radar echoes. The analysis shows that the radar would provide valuable data on the location and intensity of the hurricane-force winds.
Hurricanes cause sporadic devastation along the Gulf and Atlantic coasts despite intensive research and a warning system that integrates satellite surveillance, aircraft reconnaissance, and a network of coastal radars. Part of the devastation must be attributed to inadequate public preparation and response and part to the limits of weather predictability, but part must be attributed to the use of an outmoded radar system. Although there now exist Doppler radars that provide real-time colored displays of the wind structure in storms, the radars that comprise the last line of defense in the national hurricane warning service provide no wind information.
To support the contention that the coastal network should consist of Doppler radars, this paper develops a scenario in which a hurricane is approaching Galveston. A Doppler radar is imagined to be located at Galveston. The hurricane is assigned an average wind structure from which the field of wind components directed towards the radar is computed. After color coding the entire wind field, the corresponding color-coded radar display is obtained for a plausible distribution of radar echoes. The analysis shows that the radar would provide valuable data on the location and intensity of the hurricane-force winds.
Abstract
Profiles of refractive index over the West Indies based on the mean atmospheres of Gutnick and Jordan give no indication of the duct that is usually detected by radar at the trade-wind inversion. The discrepancy is attributed to the humidities that Gutnick assigns during “motorboating” of the radiosonde. If the presence of the duct is accepted at the trade-wind inversion and the necessary humidity profile inferred therefrom, compatible profiles of dew point and index of refraction are obtained.
Abstract
Profiles of refractive index over the West Indies based on the mean atmospheres of Gutnick and Jordan give no indication of the duct that is usually detected by radar at the trade-wind inversion. The discrepancy is attributed to the humidities that Gutnick assigns during “motorboating” of the radiosonde. If the presence of the duct is accepted at the trade-wind inversion and the necessary humidity profile inferred therefrom, compatible profiles of dew point and index of refraction are obtained.
Abstract
A series of rawins, tracked by an M-33 radar, was carried out at Palestine, Texas, in November 1965. Ascent rates of about 60 m./min. and recording of balloon coordinates at half-minute intervals were used to give fine resolution. In addition to horizontal winds, the flights were analyzed for the vertical wind component, and ascent-rate of the balloon.
The results suggest that some inferences as to thermal structure in the surface layer can be drawn from precision balloon tracking. A uniform rate of ascent is associated with inversion conditions. An ascent that shows two rates, a faster one through the first few hundred meters and a slower one above, occurs when the surface layer is undergoing mixing of either convective or mechanical origin. Attempts to fit an expression of the form
to the profile of wind speed in the surface-based layer agreed moderately well with the expectation of p≦1/7 for unstable layers and p≧1/3 for inversions. This somewhat weak indication was often supported by the profile of wind direction—uniform direction or slight backing through the mixed layer with rapid veering above. During ascent through unstable layers maximum vertical wind components generally exceeded 0.8 m./sec.; through stable layers they generally subceeded 0.3 m./sec.
Abstract
A series of rawins, tracked by an M-33 radar, was carried out at Palestine, Texas, in November 1965. Ascent rates of about 60 m./min. and recording of balloon coordinates at half-minute intervals were used to give fine resolution. In addition to horizontal winds, the flights were analyzed for the vertical wind component, and ascent-rate of the balloon.
The results suggest that some inferences as to thermal structure in the surface layer can be drawn from precision balloon tracking. A uniform rate of ascent is associated with inversion conditions. An ascent that shows two rates, a faster one through the first few hundred meters and a slower one above, occurs when the surface layer is undergoing mixing of either convective or mechanical origin. Attempts to fit an expression of the form
to the profile of wind speed in the surface-based layer agreed moderately well with the expectation of p≦1/7 for unstable layers and p≧1/3 for inversions. This somewhat weak indication was often supported by the profile of wind direction—uniform direction or slight backing through the mixed layer with rapid veering above. During ascent through unstable layers maximum vertical wind components generally exceeded 0.8 m./sec.; through stable layers they generally subceeded 0.3 m./sec.
Abstract
Inversions at Point Arguello, California, as detected in 4½ years by rawinsondes at 0400 and 1600 PST, are related to surface wind direction and speed and surface temperatures. Nocturnal inversions based below 1000 ft msl have their maximum frequency in winter and their minimum in summer. Most of them occur with downslope surface winds. Afternoon inversions are most frequent in July and least frequent in January. Nocturnal surface inversions appear to develop when the downslope drainage air from the interior is cool enough to undercut the marine layer. There is evidence that the critical surface temperature for this to take place is 9C.
Abstract
Inversions at Point Arguello, California, as detected in 4½ years by rawinsondes at 0400 and 1600 PST, are related to surface wind direction and speed and surface temperatures. Nocturnal inversions based below 1000 ft msl have their maximum frequency in winter and their minimum in summer. Most of them occur with downslope surface winds. Afternoon inversions are most frequent in July and least frequent in January. Nocturnal surface inversions appear to develop when the downslope drainage air from the interior is cool enough to undercut the marine layer. There is evidence that the critical surface temperature for this to take place is 9C.
Abstract
Winds were measured in and above a tropical rain forest in northern Colombia. Wind speeds below the canopy are only 1 to 5 per cent of that measured 50 ft above the canopy. Wind directions below the canopy appear to be disorganized.
Abstract
Winds were measured in and above a tropical rain forest in northern Colombia. Wind speeds below the canopy are only 1 to 5 per cent of that measured 50 ft above the canopy. Wind directions below the canopy appear to be disorganized.
