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Aspergillus flavus Link ex Fries was grown on cassava (Manihot utilissima) and Czapek-Dox media at 31 ± 1°C and 90 per cent relative humidity for 8 weeks. Isolation and purification of the toxic and carcinogenic metabolic products of the mould by paper and thin layer chromatography are described. High concentrations of aflatoxin B1, B2, G1 and G2 were synthesized by the mould grown on cassava for 4 weeks. In addition to these four major toxic components, 9 other fluorescent materials were observed on the chromatograms of crude products from cassava. It is concluded that the high moisture, high polysaccharide and low nitrogen content of cassava constitute a favourable nutritional condition at high temperatures and high relative humidity for the growth of A. flavus and the synthesis of relatively high concentrations of aflatoxin. This could represent a serious health hazard in the moist tropics. [ABSTRACT FROM AUTHOR]

Information about several papers discussed at the Royal Meteorological Society held in London, England on May 15, 1946. In the absence of the president and vice-president, Dr. H. Godwin assumed as chairman of the organization. During the event, they discussed variations in climate including the greater incidence of frost in a narrow valley situated on the slopes of the Malverns.

The article presents a study which examines the distribution of light reaching the ground vegetation in a tropical rain forest in Singapore. A data on the occurrence of sunflecks, and also on lighting conditions in the shade when the sun was shining, and obscured by cloud is provided. The pattern of light on sample plots on the forest floor under cloudy conditions is also examined. The pattern on the forest floor under sunny conditions without sunflecks and the pattern on the forest floor under cloudy conditions were compared.

The article examines the relation of evaporativity to plants and animals. It investigates the conditions determining rates of evaporation from organisms in freezing weather. It discusses some new arrangements whereby porous-porcelain atmometers may be guarded from frost injury in short period of freezing weather. The experimentation was carried out at the Laboratory of Plant Physiology of the Johns Hopkins University in Baltimore, Maryland during the winter of 1927 to 1928. It emphasizes that direct measurement of evaporation in freezing weather may be based on the vaporization of either liquid or solid water.

Incoming air from an ocean may either supply heat to a land area or serve as an energy sink. A marked example of the energy sink phenomenon occurs in a coastal valley of California. Advective cooling resulted in much lower evapotranspiration than amounts reported for interior locations during the two months studied, July and September. Evapotranspiration from irrigated ryegrass was equivalent to about 2/3 of net radiation on clear days. This ratio is lower than the 8/10 or 9/10 commonly observed in humid interior areas and is much lower than amounts reported for interior desert conditions. Overcast days having low net radiation did not produce amounts of evapotranspiration that were proportionally as low. This observation indicated that there was a trade off beween radiation and advection under these coastal conditions where a critical balance existed between air and surface temperatures. [ABSTRACT FROM AUTHOR]

The article reports that air pilots must possess basic knowledge of meteorology. It will enable them to read a weather map and understand the weather significance of the clouds. The study of meteorology will also help them in their profession. For a pilot, it is essential to understand the significance of clouds and other weather appearances. An aviator should also know whether the expected storm is developing sooner than anticipated.

The object of the investigation was to study the relation between the movements of the guard cells and the osmotic value, as well as the influence of the water deficit of the leaf on these two phenomena. The experimental objects consisted of leaves of Vicia Faba, Rumex acetosa and Rheum rhaponticum. The stomatal aperture, osmotic value and water deficit were measured at fixed intervals during the day. During this time, the leaves were kept in light and saturated humidity at a temperature of 20-22° C. With a suboptimal water deficit, the guard cells are found to open in light and close in darkness. Their osmotic value rises during the opening movement and falls during the closing movement. The course is thus in agreement with the traditional conception of the stomatal movements as a function of the light and of the enzymic metabolism; it is represented by the schema: Osmotic value rises Light → Photoactive opening Photoactive and passive closure ← Darkness Osmotic value falls. Pressure from epiderma cells positive. With a supraoptimal water deficit, the movements of the guard cells are controlled mainly by the water deficit. Three kinds of effect can be distinguished: 1. The deficit initiates stomatal closure. The process has been described earlier and denoted as the hydroactive stomatal closure (Såtlfelt 1929). The hydroactive stomatal closure and the photoactive opening together form the hydrophotic regulator of the water balance. 2. The deficit decreases the osmotic value of the guard cells. It could not however, be determined whether the osmotic value starts to fall before, concurrently with or after initiation of the closing movements of the stomata. 3. The deficit decreases the light sensitivity of the guard cells to the photic opening process. This is because hydroactive closure has an after-effect, which persists for several hours after the deficit has decreased or regressed, and which makes the guard cells indisposed to photic opening. A safety mechanism is inherent in this inhibiting reaction; it protects the leaf from rapidly developing large water deficits which would arise on light, warm days, if the photoactive opening mechanism continued unchanged after the deficit had regressed owing to stomatal closure. Thus, it is found that the photoactive opening reaction is also controlled by a sensitivity regulator, which is initiated by the deficit when it reaches high supraoptimal values. If the safety mechanism is also included, the hydrophotic regulator can be represented by the schema: Osmotic value rises Light → Photoactive opening Hydroactive closure. Decrease in ← Supraoptimal water light sensitivity of guard cells. [ABSTRACT FROM AUTHOR]

The article presents a survey regarding the technical advice nature which is necessary when treating land affected by industry or by other forms of intensive human use conducted by the British Ecological Society. The survey focuses on the identification of environmental features inhibiting re-vegetation because it is not well understood and it seems to restore the flexibility of re-use to dilapilated land and may create a more successful reclamation. It involves advice given by a multi-disciplinary group from the fields of meteorology, hydrology, and microbiology. The article suggested that competent interpretation of environment analysis data can be gathered by a multi-disciplinary group working together.

The article describes the rate of development of several characteristics of the forest floor and changes in the mineral-soil properties of reaction (pH), organic carbon, total nitrogen, calcium carbonate and bulk density of the fine earth. The changes are linked to both the age of the surface and to the developing vegetation, and one significant ecological factor for purposes of general orientation is the regional climate. Gustavus, Cape Spencer and Haines are the meteorological stations that are near to Glacier Bay, Alaska. The three types of vegetation are the pioneer community, the willow-alder thicket and the spruce forest.

The article presents a discussion about climatic classification based for East African biology. The article provides a brief introduction and knowledge about the relevant characteristics of East Africa. It explores the classifications of climate using Köppen system and derivatives, functions of rainfall, evaporation, and temperature, and months with a defined climatic ratios. The article is also supplemented with details regarding the importance of mist and cloud, meteorology, and precipitation.

The article presents a comparison of the climate of São Paulo, Brazil and Pine Bluff, Arkansas. São Paulo is located in the South American republic of Brazil. The city is close to the southern escarpment of the Brazilian Highland. Pine Bluff, Arkansas, is a medium sized city located on the south bank of the Arkansas River. The climatic reports of the area depicts that São Paulo has a mean annual temperature of 63.7° F and a total annual rainfall of 53.1 inches. The records shows that the April and October temperatures are about the same in both places and that maximum precipitation at both stations occurs in January. When the monthly mean temperatures and rainfalls at São Paulo were compared with the same figures for Pine Bluff, it becomes apparent that the climatic patterns are not similar in the two locations.

The article discusses the multifarious facts and concepts involved in various courses of study in elementary science and inadequacy of training of science teachers in the U.S. In addition, it also outlines some recommendations for the improvement of training of prospective elementary science teachers. Elementary teachers should be provided with a special course involving simple, basic, fundamental scientific facts and principles. This course must be a laboratory course involving fundamental facts and principles which may be utilized in the elementary classroom. The courses are highlighted as agriculture, botany, zoology, forestry, chemistry, physics, astronomy, geology, geography, meteorology, physiology, and hygiene. The science course should be associated with a method course in elementary science in which prospective teachers are provided an insight into the broader purposes and significance of science in the elementary curriculum.

Discusses the biting habits of adult biting fly Leptoconops Bequaerti. Effect of meteorological conditions on the biting activity of the fly; Biting activity of the fly during different intervals of the day; Diurnal nature of the fly.

The exchange of heat across the air-water interface is one of the more important factors that govern the temperature of a water body. The net rate of heat exchange at the water surface is the sum of the rates at which heat is transferred by radiative processes, by evaporation, and by conduction between water and overlying air. The net rate can be evaluated in terms of a thermal exchange coefficient and an equilibrium temperature, both of which depend on observable meteorological variables. Any one of the many evaporation formulas and mathematical descriptions of the other heat exchange processes may be used to develop equations involving the thermal exchange coefficient and equilibrium temperature. Such equations are useful in developing relations that describe the temporal and spatial temperature distributions within a water body. They provide additional insight into the effects of meteorological conditions on water temperatures, and they facilitate estimates of various terms of the heat budget. [ABSTRACT FROM AUTHOR]

An 11-year continuous record from 49 recording rain gages on 400 square miles in central Illinois has been used to derive characteristic area-depth relations in heavy rainstorms for storm periods of 30 minutes to 48 hours on areas of 50, 100, 200, and 400 square miles. First, eight general equations were statistically tested to determine the most appropriate fitting method for the area-depth curve. Over-all, an equation relating rainfall depth to the square root of the area received the highest score. However, the equation that fit best was found to vary with areal size, mean rainfall, and storm duration, which, in turn, reflected general trends in relative variability and skewness of the rainfall spatial distribution. Because of the high degree of variability in the area-depth relation between storms, the analytical results have been presented as probability distributions for given sets of conditions with respect to area, storm duration, and rainfall volume. Thus, the user is provided with both average curves and curves applicable to more extreme patterns of storm rainfall. [ABSTRACT FROM AUTHOR]

To apply a complete energy balance to the computation of evaporation or snowmelt, radiation data are necessary. At present there is a reasonably adequate network of incident solar radiation stations. However, a network of all-wave radiometers does not exist. It is therefore evident that to apply the energy budget technique to hydrological problems, incident long-wave radiation has to be estimated. An empirical equation is developed by which incident long-wave radiation can be computed from observations of surface air temperature, vapor pressure, and incident solar radiation. Based on comparisons of estimated and observed incident long-wave radiation at six locations, the following conclusions seem warranted: (1) The equation should give results comparable within a few percent on a long-term basis (six months or longer); (2) For any specific atmospheric condition, there seems to be no tendency for the equation to over or under compute or to give increased scatter; (3) When data for periods of six-months or more were analyzed, correlation coefficients of approximately 0.90 were obtained between computed and observed daily radiation values. [ABSTRACT FROM AUTHOR]

The meteorology of a mountainous watershed in the Alberta Rockies is shown to be strongly influenced by upslope-downslope diurnal wind circulations during rain-free periods of observation in August, 1965. The evapotranspiration from the forest is inferred from measurements of net radiation above the canopy and from vertical temperature gradients obtained from an 80-ft tower. The forest water loss during August rain-free periods is estimated to be between 0.15 and 0.6 gm/cm2/day with high confidence, or between 0.25 and 0.48 gm/cm2 with somewhat less confidence. A 'best' engineering estimate of evapotranspiration is 0.3 gm/cm2/day. [ABSTRACT FROM AUTHOR]

During October 1954 heavy rains, which exceeded normal by 300%, occurred in the Chiriqui province of Panama, causing extensive flooding. The copious rainfall is believed to be caused by a small tropical storm and the remnants of a polar air mass. [ABSTRACT FROM AUTHOR]

Data from four concentrated rain gage networks in Illinois were used to investigate the effect of natural rainfall variability upon verification of cloud seeding experiments in midwestern, warm season rainfall on areas of county size or less. Hypothetical seeding experiments were made on network data for seasonal periods of 1 to 5 months and or durations of 1 to 10 years. Both target-control and single-area randomized experiments were investigated, and the data were grouped into air mass storms and all storms combined. Results indicated that the single-area sampling experiments are influenced more by the effects of natural rainfall variability than the target control type, but that the background interference is substantial in both cases. The study clearly illustrates the pitfalls in judging the results of cloud seeding on short-term experiments, and shows how verification may be affected by rain gage density and size of sampling area. [ABSTRACT FROM AUTHOR]

Using a combination of a surface energy balance equation and an approximate expression of water vapor and sensible heat transfer, an equation is formulated relating potential evaporation for net radiation, ambient air properties, and surface roughness. As an improvement over the earlier Penman version, the proposed model contains no empirical constants or functions. Tests of the model in Phoenix, Arizona, using open water, wet bare soil, and well watered alfalfa, show excellent agreement of calculated and measured values on an hourly and daily basis under a variety of circumstances. Test conditions typically included advection of sensible heat to the evaporating surface in a large proportion to the latent heat flux, as well as high values of radiant flux, ambient temperatures, and vapor pressure deficits. The use of daily average values for the weather variables in the model, rather than hourly data, did not give appreciably different results or conclusions on a series of mostly clear days, suggesting that the combination model is not only accurate but also practical and generally applicable. (Key words: Evaporation; evapotranspiration; meteorology) [ABSTRACT FROM AUTHOR]

This article describes the weather in England and Wales during the spring and summer of 1963. The prolonged severe winter of 1962-63 effectively came to an end during the first week of March. South-westerly winds with considerable rain swept over the country and March 6th was the first day of the year without frost. June was warm at first with scattered thunderstorms but changed later to a cool and unsettled type of weather. This persisted for most of July until the last week when a dry warm spell occurred. August remained cool and dull throughout with considerable rain in eastern counties from Northumberland to Essex.