NASA's rotorcraft icing research program

The objective of the NASA aircraft icing research program is to develop and make available icing technology to support the needs and requirements of industry for all weather aircraft designs. While a majority of the technology being developed is viewed to be generic (i.e., appropriate to all vehicle classes), vehicle specific emphasis is being placed on the helicopter due to its unique icing problems. In particular, some of the considerations for rotorcraft icing are indicated. The NASA icing research program emphasizes technology development in two key areas: ice protection concepts and icing simulation (analytical and experimental). The NASA research efforts related to rotorcraft icing in these two technology areas will be reviewed

Soil Moisture Situation 1957

Your bank account of soil moisture can\u27t be overdrawn - nature won\u27t advance the funds. Your account for 1957 crops depends on the current balance plus any amount of moisture added, absorbed and held

Precipitation probabilities in the North Central States

Cover title.Includes bibliographical references

Impact of the Holocene Transgression on the Atlantic Coastline of Nova Scotia

As analogs for impact of a future sea-level rise on the coast of Nova Scotia (eastern Canada), geological data and information on relative sea-level changes are examined at three different time scales. Relative sea level rose swiftly during the early Holocene, at a maximum rate of 11 m/ka at 7500 radiocarbon years BP. Freshwater, salt-marsh, and estuarine sediments that formed during this period have been located on the inner shelf. After 5000 BP the rate slackened to about 2 m/ka. Despite overall submergence and coastal retreat since that time, gravel barriers have persisted where large amounts of sediment have been added to the littoral system by erosion of glacial deposits. The barriers often display evidence of early progradational phases in the form of gravel beach ridges, partly or wholly submerged in lagoons behind contemporary storm beaches. Tide-gauge data from the past century show submergence rates averaging 3.5 mm/a, well in excess of the longterm trend. The response of the coastline to this rapid rise is complex. Unconsolidated cliffs (bluffs) retreat at up to 5 m/a during initial exposure to wave attack and during extreme storm events, but at lesser rates (8 m/a) in some locations, but low elsewhere, in some cases showing almost no movement over the past 10 years, and neighbouring beaches are sometimes observed to behave in completely different ways. Sediment released by coastal erosion finds its way into nearby estuaries, causing growth of flood-tidal deltas and marsh aggradation. If a global rise in sea level occurs, the processes of erosion and sedimentation operating along the coast of Nova Scotia during the Holocene are expected to continue in a similar fashion, but rates of change will increase at many locations.Les données géologiques et les connaissances sur les changements du niveau marin relatif sont étudiées à trois échelles temporelles en tant qu'analogues des conséquences d'une future hausse du niveau marin sur la côte de la Nouvelle-Écosse. Le niveau marin relatif s'est rapidement élevé au cours de l'Holocène inférieur, jusqu'au taux maximal de 11 m/ka à 7500 BP. Des sédiments estuariens ou issus de marais salants et d'eau douce datant de cette période ont été localisés sur le plateau continental intérieur. Après 5000 BP le taux a diminué jusqu'à 2 m/ka. En dépit de la submersion de la région côtière et de son dégagement subséquent, les cordons littoraux de gravier ont persisté là où de grandes quantités de sédiments ont été mis en place sur le littoral par érosion des dépôts glaciaires. Les cordons montrent souvent des indices de phases de progression sous la forme de crêtes de graviers, partiellement ou entièrement submergés dans les lagunes situées derrière les plages de tempêtes contemporaines. Les données marégraphiques du siècle dernier font ressortir un taux de submersion d'environ 3,5 mm/a, taux nettement plus élevé que celui de la tendance à long terme. La réponse du littoral à cette hausse rapide est complexe. Les falaises non consolidées peuvent reculer jusqu'à 5 m/a au début de leur exposition aux fortes vagues et pendant les plus fortes tempêtes et à un rythme beaucoup plus lent (8 m/a) par endroits, lent ailleurs; certaines plages sont presque immobiles depuis 10 ans, alors que les plages voisines se comportent de façon tout à fait différente. Les sédiments libérés par l'érosion littorale se retrouvent dans les estuaires les plus proches, provoquant l'expansion des deltas d'inondation et l'extension des marais. Si une hausse globale du niveau marin survenait, les processus d'érosion et de sédimentation qui se sont manifestés le long de la côte de la Nouvelle-Écosse pendant l'Holocène agiront de façon semblable, mais le rythme des changements augmentera dans plusieurs sites

The climate of Iowa: the occurrence of freezing temperatures in spring and fall

No type of agriculture can be establish ed profitably in a region unless the risk of loss to that type o f agriculture from unfavorable weather conditions is more than balanced by the profits of other times. The farmer should know the risk involved in raising a given crop at a given time. One of these weather risks is minimum temperatures. Minimum temperatures are important at all times of the year, but at certain times, the occurrence of especially critical temperatures is of extreme importance. A killing freeze is often a factor limiting production. Killing freezes may occur in the spring to damage perennial crops that start growth early in the season, o r annual plants that get an early start and are then injured by a late spring freeze . Killing freezes may also occur in the fall and terminate the growing season. In either case , severe damage can be caused and heavy losses incurred . Injury may also occur to perennial crop s from sub zero winter temperatures, but that type of freezing weather will not be covered in this report.https://lib.dr.iastate.edu/specialreports/1005/thumbnail.jp

Relative Impact of Highway Construction on Wetland Hydrology in Environmentally Sensitive Areas in Southeast Louisiana

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv