Radioactive Hailstones in the District of Columbia Area, May 26, 1953

1954 ◽  
Vol 35 (6) ◽  
pp. 245-249 ◽  
Author(s):  
Gilbert Jaffe ◽  
Walter Wittmann ◽  
Charles C. Bates

At about 2000Z, 26 May 1953 the District of Columbia area experienced a hailstorm in which individual hailstones ranged up to the size of tennis balls. Determinations of the radioactive count of the water content of these hailstones and of roof gravels indicate that considerable material was brought to earth by the hailstorm from the explosion of the atomic cannon shell 29 hours earlier some 2000 airline miles away in Nevada. The air-flow pattern at upper levels proves to have been around a high-pressure ridge located between the two sites. Such a pattern permitted the arrival of such radioactive material over the District of Columbia area within the time noted.

2020 ◽  
Author(s):  
Jianying Feng ◽  
Yu Zhang ◽  
Suping Wang

<p>In 2018, severe meteorological drought occurred in the southwest of Northeast China, the  east-central of Inner Mongolia and the east of North China. Drought shows obvious regional and stage nature .In early March, mild to moderate drought appeared in North China, followed by severe drought in parts of northern and eastern of Hebe province. After the middle of April, the drought was alleviated obviously, and the drought in the southwest of Northeast China began to show signs. In  early May, there was mild to moderate drought in the central and eastern part of Inner Mongolia, and the drought in Northeast China developed. From June to early August, severe drought and above occurred in parts of Liaoning province , Inner Mongolia and North China. In mid-August, in addition to Liaoning province and North China, there were scattered light to moderate drought, drought relief in the northern China. In early September, the drought in North China increased and the range spread northward, and there were droughts of different degrees in the whole North China.In winter, there is only mild drought in North China.</p><p>The drought in this region has affected the agricultural production in different degrees. Spring sowing is blocked in the east of Inner Mongolia and the west of Northeast China, and high temperature in summer leads to the development of drought, corn and rice and other crops are adversely affected.</p><p>From spring to autumn, the precipitation in most parts of the drought disaster  area is less than 10-40%, and the temperature is higher than 1-2 ℃. The lack of precipitation and abnormal high temperature accelerated the loss of surface water, which resulted in the occurrence of drought in this area.</p><p>In spring of 2018, the middle and high latitudes are generally controlled by flat air flow, which is not conducive to the establishment of trough ridge, making the northern dry area lack of favorable precipitation conditions; in summer and autumn, the existence of Baikal Lake high-pressure ridge, resulting in circulation patterns that are not conducive to the precipitation conditions in the northern dry area. Among them, the obvious flat air flow in spring and the obvious high pressure ridge in summer are the main reasons for the outstanding drought in spring and summer in the northern arid area.</p>


2014 ◽  
Vol 12 (9) ◽  
pp. 908-916 ◽  
Author(s):  
Marilia Ramalho Fontenelle ◽  
Sylvie Lorente ◽  
Leopoldo Eurico Gonçalves Bastos

Author(s):  
B. P. Huynh

Natural-ventilation flow induced in a real-sized rectangular-box room fitted with a solar chimney on its roof is investigated numerically, using a commercial CFD (Computational Fluid Dynamics) software package. The chimney in turn is in the form of a parallel channel with one plate being subjected to uniform solar heat flux. Ventilation rate and air-flow pattern through the room are considered in terms of the heat flux for two different locations of the room’s inlet opening. Chien’s turbulence model of low-Reynolds-number K-ε is used in a Reynolds-Averaged Navier-Stokes (RANS) formulation. It is found that ventilation flow rate increases quickly with solar heat flux when this flux is low, but more gradually at higher flux. At low heat flux, ventilation rate is not significantly affected by location of the inlet opening to the room. On the other hand, at high heat flux, ventilation rate varies substantially with the opening’s location. Location of the inlet opening to the room also affects strongly the air-flow pattern. In any case, ample ventilation rate is readily induced by the chimney.


2015 ◽  
Author(s):  
A. Idris ◽  
B. P. Huynh ◽  
Z. Abdullah

Ventilation is a process of changing air in an enclosed space. Air should continuously be withdrawn and replaced by fresh air from a clean external source to maintain internal good air quality, which may referred to air quality within and around the building structures. In natural ventilation the air flow is due through cracks in the building envelope or purposely installed openings. Its can save significant amount of fossil fuel based energy by reducing the needs for mechanical ventilation and air conditioning. Numerical predictions of air velocities and the flow patterns inside the building are determined. To achieve optimum efficiency of natural ventilation, the building design should start from the climatic conditions and orography of the construction to ensure the building permeability to the outside airflow to absorb heat from indoors to reduce temperatures. Effective ventilation in a building will affects the occupant health and productivity. In this work, computational simulation is performed on a real-sized box-room with dimensions 5 m × 5 m × 5 m. Single-sided ventilation is considered whereby openings are located only on the same wall. Two opening of the total area 4 m2 are differently arranged, resulting in 16 configurations to be investigated. A logarithmic wind profile upwind of the building is employed. A commercial Computational Fluid Dynamics (CFD) software package CFD-ACE of ESI group is used. A Reynolds Average Navier Stokes (RANS) turbulence model & LES turbulence model are used to predict the air’s flow rate and air flow pattern. The governing equations for large eddy motion were obtained by filtering the Navier-Stokes and continuity equations. The computational domain was constructed had a height of 4H, width of 9H and length of 13H (H=5m), sufficiently large to avoid disturbance of air flow around the building. From the overall results, the lowest and the highest ventilation rates were obtained with windward opening and leeward opening respectively. The location and arrangement of opening affects ventilation and air flow pattern.


2015 ◽  
Vol 60 (9) ◽  
pp. 2674-2683 ◽  
Author(s):  
Louis V. Jasperson ◽  
Jeong Won Kang ◽  
Chul Soo Lee ◽  
Don Macklin ◽  
Paul M. Mathias ◽  
...  

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