Climatological Aspects of Radiation Fog Occurrence at Albany, New York

Meyer, M.; Lala, G. Garland

doi:10.1175/1520-0442(1990)003<0577:caorfo>2.0.co;2

Cited by 60 publications

(55 citation statements)

References 10 publications

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“…7). This fog may have been formed by radiative cooling of moisture derived from local waters as wind directions were variable among sites while wind speeds at each site were consistent with those associated with radiation fog (< 2.5 m s -1 ) (Roach et al, 1976;Meyer and Lala, 1990;Tardif and Rasmussen, 2007) (Table S3). Or, this fog was formed by the perpetuation of mixed fog inland with addition of local moisture along its trajectory similar to that proposed for the 18 th June 2016.…”

Section: Classification Of Fog On the 19mentioning

confidence: 77%

“…Therefore we did not characterize mixed fog because the Gobabeb fog sample was the only unevaporated mixed fog sample, d (+5.5‰). Both mixed fog and radiation fog require similar conditions for formation e.g., radiative cooling and calm winds (< 2.5 m s -1 ) (Roach et al, 1976;Meyer and Lala, 1990;Tardif and Rasmussen, 2007), conditions that were prevalent during the fog events at all sites (Table S3). However, there was a noticeable difference in the degree of radiative cooling and RH during the fog event between the mixed fog sites and the radiation fog sites.…”

Section: Resultsmentioning

confidence: 99%

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Fog Spatial Distributions over the Central Namib Desert - An Isotope Approach

Kaseke

Tian

Wang

et al. 2018

Aerosol Air Qual. Res.

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Fog is a characteristic feature of the Namib Desert and is essential to life in this fog dependent system. It is often acknowledged that advective fog from the ocean is the dominant fog type over the Namib Desert fog-zone but recent evidence suggests that other fog types occur in this area. Knowledge of the existence and spatial distribution of different fog types will enhance the mechanistic understanding of fog formation and potential changes in this region, but such knowledge is limited in literature. In this study, we investigated fog spatial variations within the Namib Desert fog-zone by applying stable isotope (δ 18 O and δ 2 H) techniques to differentiate various fog types and identify their source waters. Isotope based results showed that at least three types of fog (advective, radiation and mixed) occurred in this region and what appears as a single fog event may include all three types. Results suggest that radiation fog was the dominant fog type during our study period. The results also suggest that advective fog (with Atlantic Ocean origins) either dissipated 30-50 km inland and the residual humidity combined with locally derived moisture to form mixed fog or advective fog incorporated local moisture along its trajectory inland resulting in mixed fog. Fog in the Namib Desert was consistently depleted in 18 O and 2 H compared to rainfall and this was attributed to sub-cloud evaporation of the rainfall as well as different sources of fog and rainfall. Sub-cloud evaporation led to enrichment of 18 O and 2 H in rainfall beyond that of the first stage condensate, fog. Advective fog is often considered the architect of the fog-zone in the Namib Desert, but our results demonstrated multiple dominant fog types during the study period, suggesting knowledge of both fog frequency and fog type is needed to better predict climate change impacts on the fog-zone.

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Section: Classification Of Fog On the 19mentioning

confidence: 77%

Section: Resultsmentioning

confidence: 99%

Fog Spatial Distributions over the Central Namib Desert - An Isotope Approach

Kaseke

Tian

Wang

et al. 2018

Aerosol Air Qual. Res.

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“…However, such thresholds, discussed by Jiusto (1981), also vary, between 400 m (e.g. Meyer and Lala, 1990) and 5 km (e.g. Jiusto, 1981).…”

Section: Fogmentioning

confidence: 99%

Enhanced extinction of visible radiation due to hydrated aerosols in mist and fog

Elías¹,

Dupont

Hammer

et al. 2015

Atmos. Chem. Phys.

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Abstract. The study assesses the contribution of aerosols to the extinction of visible radiation in the mist-fog-mist cycle. Relative humidity is large in the mist-fog-mist cycle, and aerosols most efficient in interacting with visible radiation are hydrated and compose the accumulation mode. Measurements of the microphysical and optical properties of these hydrated aerosols with diameters larger than 0.4 µm were carried out near Paris, during November 2011, under ambient conditions. Eleven mist-fog-mist cycles were observed, with a cumulated fog duration of 96 h, and a cumulated mist-fogmist cycle duration of 240 h.In mist, aerosols grew by taking up water at relative humidities larger than 93 %, causing a visibility decrease below 5 km. While visibility decreased down from 5 to a few kilometres, the mean size of the hydrated aerosols increased, and their number concentration (N ha ) increased from approximately 160 to approximately 600 cm −3 . When fog formed, droplets became the strongest contributors to visible radiation extinction, and liquid water content (LWC) increased beyond 7 mg m −3 . Hydrated aerosols of the accumulation mode co-existed with droplets, as interstitial non-activated aerosols. Their size continued to increase, and some aerosols achieved diameters larger than 2.5 µm. The mean transition diameter between the aerosol accumulation mode and the small droplet mode was 4.0 ± 1.1 µm. N ha also increased on average by 60 % after fog formation. Consequently, the mean contribution to extinction in fog was 20 ± 15 % from hydrated aerosols smaller than 2.5 µm and 6 ± 7 % from larger aerosols. The standard deviation was large because of the large variability of N ha in fog, which could be smaller than in mist or 3 times larger.The particle extinction coefficient in fog can be computed as the sum of a droplet component and an aerosol component, which can be approximated by 3.5 N ha (N ha in cm −3 and particle extinction coefficient in Mm −1 ). We observed an influence of the main formation process on N ha , but not on the contribution to fog extinction by aerosols. Indeed, in fogs formed by stratus lowering (STL), the mean N ha was 360 ± 140 cm −3 , close to the value observed in mist, while in fogs formed by nocturnal radiative cooling (RAD) under cloud-free sky, the mean N ha was 600 ± 350 cm −3 . But because visibility (extinction) in fog was also lower (larger) in RAD than in STL fogs, the contribution by aerosols to extinction depended little on the fog formation process. Similarly, the proportion of hydrated aerosols over all aerosols (dry and hydrated) did not depend on the fog formation process.Measurements showed that visibility in RAD fogs was smaller than in STL fogs due to three factors: (1) LWC was larger in RAD than in STL fogs, (2) droplets were smaller, (3) hydrated aerosols composing the accumulation mode were more numerous.

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“…4). A large majority of these events were associated with anticyclonic large-scale weather conditions (Tables 3 and 4), typical of both radiation and stratus-lowering fog scenarios (e.g., Meyer and Lala 1990;Wobrock et al 1992), each type representing about 40% of all fog events. The more marginal fog types, corresponding to two advection fog events, a morning transition fog, and one precipitation fog event, occurred during short-lived anticyclonic or perturbed weather conditions.…”

Section: Parisfog: Over 100 Fog and Near-fog Situationsmentioning

confidence: 99%

“…Early studies revealed that the development of radiation fog results from the balance between radiative cooling and turbulent mixing [e.g., Roach et al (1976) based on observations performed in Cardington, United Kingdom]. Other datasets were put together to focus on radiation fog such as the Fog-82 campaign in Albany, New York (Meyer et al 1986), and the Lille-88 and Lille-91 field experiments in northern France (Guédalia and Bergot 1994). The role of turbulence was investigated using measurements performed at the Cabauw experimental site in the Netherlands (Duynkerke 1991(Duynkerke , 1999.…”

mentioning

confidence: 99%

Parisfog

Haeffelin¹,

Bergot²,

Elías³

et al. 2010

Bull. Amer. Meteor. Soc.

139

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, T. bergoT, T. elias, r. Tardif, d. Carrer, P. CHazeTTe, M. ColoMb, P. drobinski, e. duPonT, J.-C. duPonT, l. goMes, l. Musson-genon, C. PieTras, a. Plana-faTTori, a. ProTaT, J. rangognio, J.-C. rauT, s. réMy, d. riCHard, J. sCiare, and X. zHang A field experiment covering more than 100 fog and near-fog situations during the winter of 2006-07 investigated the dynamical, microphysical, and radiative processes that drive the life cycle of fog.

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Climatological Aspects of Radiation Fog Occurrence at Albany, New York

Cited by 60 publications

References 10 publications

Fog Spatial Distributions over the Central Namib Desert - An Isotope Approach

Fog Spatial Distributions over the Central Namib Desert - An Isotope Approach

Enhanced extinction of visible radiation due to hydrated aerosols in mist and fog

Parisfog

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