Touching the Clouds Activity Guide
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Precipitation Effects of Giant Cloud Condensation Nuclei Artificially Introduced Into Stratocumulus Clouds
Atmos. Chem. Phys., 15, 5645–5658, 2015 www.atmos-chem-phys.net/15/5645/2015/ doi:10.5194/acp-15-5645-2015 © Author(s) 2015. CC Attribution 3.0 License. Precipitation effects of giant cloud condensation nuclei artificially introduced into stratocumulus clouds E. Jung1, B. A. Albrecht1, H. H. Jonsson2, Y.-C. Chen3,4, J. H. Seinfeld3, A. Sorooshian5, A. R. Metcalf3,*, S. Song1, M. Fang1, and L. M. Russell6 1Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL, USA 2Center for Interdisciplinary Remotely-Piloted Aircraft Studies, Naval Postgraduate School, Monterey, California, USA 3California Institute of Technology, Pasadena, California, USA 4Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA 5Department of Chemical and Environmental Engineering, and Department of Atmospheric Sciences, University of Arizona, Tucson, Arizona, USA 6Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA *now at: Department of Mechanical Engineering, University of Minnesota, Minneapolis, Minnesota, California, USA Correspondence to: E. Jung ([email protected]) Received: 7 November 2014 – Published in Atmos. Chem. Phys. Discuss.: 7 January 2015 Revised: 6 April 2015 – Accepted: 11 April 2015 – Published: 22 May 2015 Abstract. To study the effect of giant cloud condensation 1 Introduction nuclei (GCCN) on precipitation processes in stratocumulus clouds, 1–10 µm diameter salt particles (salt powder) were The stratocumulus (Sc) cloud deck is the most persistent released from an aircraft while flying near the cloud top on cloud type in the world, and the variations of the cloud 3 August 2011 off the central coast of California. The seeded amount and the albedo can significantly impact the climate area was subsequently sampled from the aircraft that was system through their radiative effects on the earth system equipped with aerosol, cloud, and precipitation probes and (e.g., Hartmann et al., 1992; Slingo, 1990). -
Graphical Area Forecast User Guide a Guide for the Transition from Arfors to GAF
Graphical Area Forecast User Guide A guide for the transition from ARFORs to GAF October 2017 | Version 1.2 Graphical Area Forecast User Guide Document Control Revision history VERSION DATE DESCRIPTION AUTHOR 1 15 September 2017 Final version Elizabeth Heba Update to provide clarification on AIRMETs 1.1 13 October 2017 Elizabeth Heba and SIGMETs Update to GAF samples and worked example 1.2 20 October 2017 Additional text in Area Briefing (NAIPS) Ashwin Naidu Section Update to abbreviation examples Approval for release DATE NAME Position Signature National Manager Aviation 20 October 2017 Gordon Jackson Meteorological Services Version number Date of issue th Version 1.2 20 October 2017 © Commonwealth of Australia 2017 This work is copyright. Apart from any use as permitted under the Copyright Act 1968, no part may be reproduced without prior written permission from the Bureau of Meteorology. Requests and inquiries concerning reproduction and rights should be addressed to the Production Manager, Communication Section, Bureau of Meteorology, GPO Box 1289, Melbourne 3001. Information regarding requests for reproduction of material from the Bureau website can be found at www.bom.gov.au/other/copyright.shtml ii Graphical Area Forecast User Guide Table of Contents 1 Purpose .......................................................................................................................................... 1 2 Introduction ................................................................................................................................... -
Chapter 4: Fog
CHAPTER 4: FOG Fog is a double threat to boaters. It not only reduces visibility but also distorts sound, making collisions with obstacles – including other boats – a serious hazard. 1. Introduction Fog is a low-lying cloud that forms at or near the surface of the Earth. It is made up of tiny water droplets or ice crystals suspended in the air and usually gets its moisture from a nearby body of water or the wet ground. Fog is distinguished from mist or haze only by its density. In marine forecasts, the term “fog” is used when visibility is less than one nautical mile – or approximately two kilometres. If visibility is greater than that, but is still reduced, it is considered mist or haze. It is important to note that foggy conditions are reported on land only if visibility is less than half a nautical mile (about one kilometre). So boaters may encounter fog near coastal areas even if it is not mentioned in land-based forecasts – or particularly heavy fog, if it is. Fog Caused Worst Maritime Disaster in Canadian History The worst maritime accident in Canadian history took place in dense fog in the early hours of the morning on May 29, 1914, when the Norwegian coal ship Storstadt collided with the Canadian Pacific ocean liner Empress of Ireland. More than 1,000 people died after the Liverpool-bound liner was struck in the side and sank less than 15 minutes later in the frigid waters of the St. Lawrence River near Rimouski, Quebec. The Captain of the Empress told an inquest that he had brought his ship to a halt and was waiting for the weather to clear when, to his horror, a ship emerged from the fog, bearing directly upon him from less than a ship’s length away. -
Levey Tran ME ID: 214-765 MCEN – 4228 – 002 Flow Visualizations
Levey Tran ME ID: 214-765 MCEN – 4228 – 002 Flow Visualizations Clouds 1 Image Report The image described in this report is one that completes the Clouds 1 image assignment. The purpose of this assignment was to photograph numerous images of clouds and after many photographs were taken, the photographer was to choose a final desired cloud image. The photographs were meant to help the photographer visualize and experience the physics and flow phenomena of clouds. Too often clouds are overlooked and their beauty misjudged, but when one pays close attention and learns the physics behind the numerous types of clouds, a true appreciation can be achieved. For this assignment, I was trying to find a cloud image that resembled a stormy cloud. The image was taken on February 13, 2010 at Boulder Reservoir in the afternoon at about 2:00 PM looking between the south and south-east direction. This large group of clouds was several miles away in the distance, so the picture was taken at a small angle above the horizon. The first few images showed the horizon about 1/5th of the way from the bottom of the image. But the original photograph to this image was zoomed in and taken at an angle slightly greater than those images with the horizon in the picture. When I first began analyzing the cloud image, I had thought it looked very much like a Cumulus Congestus cloud. But I was only paying attention to the top of the cloud where it looks like cauliflowers. I also found that for it to be classified as a Cumulus Congestus, it needs to be taller than it is wide, and this cloud does not fit that description. -
Saharan Dust, Convective Lofting, Aerosol Enhancement Zones, And
PUBLICATIONS Journal of Geophysical Research: Atmospheres RESEARCH ARTICLE Saharan dust, convective lofting, aerosol enhancement zones, 10.1002/2017JD026933 and potential impacts on ice nucleation in the tropical Key Points: upper troposphere • Relative to background upper tropospheric air, an aerosol C. H. Twohy1 , B. E. Anderson2, R. A. Ferrare2 , K. E. Sauter3 ,T.S.L’Ecuyer3 , enhancement zone (AEZ) exists at the 4 fi 5 2 2 bottom edge of tropical storm anvils S. C. van den Heever , A. J. Heyms eld , S. Ismail , and G. S. Diskin • Storms affected by the SAL have more 1 2 large particles, likely mineral dust, in NorthWest Research Associates, Redmond, Washington, USA, NASA Langley Research Center, Hampton, Virginia, USA, the AEZ and these contribute to the 3Department of Atmospheric and Oceanic Sciences, University of Wisconsin, Madison, Wisconsin, USA, 4Department of background concentration Atmospheric Science, Colorado State University, Fort Collins, Colorado, USA, 5Microscale and Mesoscale Meteorology • Convective lofting of dust by Laboratory, National Center for Atmospheric Research, Boulder, Colorado, USA convective systems is predicted to enhance ice nucleating particle concentrations in the upper fi fl troposphere Abstract Dry aerosol size distributions and scattering coef cients were measured on 10 ights in 32 clear-air regions adjacent to tropical storm anvils over the eastern Atlantic Ocean. Aerosol properties in these regions were compared with those from background air in the upper troposphere at least 40 km from Supporting Information: • Supporting Information S1 clouds. Median values for aerosol scattering coefficient and particle number concentration >0.3 μm diameter were higher at the anvil edges than in background air, showing that convective clouds loft particles from the Correspondence to: lower troposphere to the upper troposphere. -
DRI Cloud Condensation Nuclei (CCN) Spectrometer Measurements
Cloud Condensation Nuclei (CCN)—water-soluble particles that cloud droplets condense upon. 10-1000 nm or 0.01-1 µm or 10-6-10-4 cm. (), CCN concentrations vary from 1-105 cm-3 CCN determine cloud droplet (5-50 µm) concentrations, which vary from 1-104 cm-3 CCN are amplified by cloud condensation from 10 to 10,000 nm (0.01 to 10 µm). Thousand in size, million in surface area, billion in volume! DRI Cloud condensation nuclei (CCN) spectrometers. Produce a field of supersaturations (S) by thermal diffusion of temperature and water vapor between two parallel plates, where cloud droplets grow on hygroscopic sample particles. More hygroscopic (e.g., larger) particles produce larger cloud droplets. Continuous flow through the cloud chamber (~30s) then into an optical particle counter (OPC). CCN spectrum is deduced from the OPC droplet spectrum. A calibration curve relates OPC droplet size to particle hygroscopicity (critical supersaturation—Sc). Calibration is done with nuclei of known composition (e.g., NaCl) and size (differential mobility analyzer—DMA— electrostatic classifier--EC). Assumes that all CCN with the same Sc regardless of composition (or size) produce the same droplet sizes. Calibration holds only if all chamber parameters (i.e., flows and temperatures) remain constant. Sc inversely proportional to number of soluble ions. Traditionally CCN plots are cumulative because clouds act cumulatively on the aerosol— all nuclei with Sc < cloud S produce “activated” cloud droplets. Also previous CCN instruments had too few data points to produce a differential spectrum. DRI CCN spectrometers have enough data points to produce differential spectra. -
Impact of Aerosols and Turbulence on Cloud Droplet Growth: an In-Cloud Seeding Case Study Using a Parcel–DNS (Direct Numerical Simulation) Approach
Atmos. Chem. Phys., 20, 10111–10124, 2020 https://doi.org/10.5194/acp-20-10111-2020 © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 License. Impact of aerosols and turbulence on cloud droplet growth: an in-cloud seeding case study using a parcel–DNS (direct numerical simulation) approach Sisi Chen1,2, Lulin Xue1,3, and Man-Kong Yau2 1National Center for Atmospheric Research, Boulder, Colorado, USA 2Department of Atmospheric and Oceanic Sciences, McGill University, Montréal, Quebec, Canada 3Hua Xin Chuang Zhi Science and Technology LLC, Beijing, China Correspondence: Sisi Chen ([email protected]) Received: 1 October 2019 – Discussion started: 21 October 2019 Revised: 6 July 2020 – Accepted: 24 July 2020 – Published: 31 August 2020 Abstract. This paper investigates the relative importance est autoconversion rate is not co-located with the smallest of turbulence and aerosol effects on the broadening of the mean droplet radius. The finding indicates that the traditional droplet size distribution (DSD) during the early stage of Kessler-type or Sundqvist-type autoconversion parameteri- cloud and raindrop formation. A parcel–DNS (direct nu- zations, which depend on the LWC or mean radius, cannot merical simulation) hybrid approach is developed to seam- capture the drizzle formation process very well. Properties lessly simulate the evolution of cloud droplets in an ascend- related to the width or the shape of the DSD are also needed, ing cloud parcel. The results show that turbulence and cloud suggesting that the scheme of Berry and Reinhardt(1974) condensation nuclei (CCN) hygroscopicity are key to the ef- is conceptually better. -
Cloud Protocols W Elcome
Cloud Protocols W elcome Purpose Geography To observe the type and cover of clouds includ- The nature and extent of cloud cover ing contrails affects the characteristics of the physical geographic system. Overview Scientific Inquiry Abilities Students observe which of ten types of clouds Intr Use a Cloud Chart to classify cloud types. and how many of three types of contrails are visible and how much of the sky is covered by Estimate cloud cover. oduction clouds (other than contrails) and how much is Identify answerable questions. covered by contrails. Design and conduct scientific investigations. Student Outcomes Use appropriate mathematics to analyze Students learn how to make estimates from data. observations and how to categorize specific Develop descriptions and predictions clouds following general descriptions for the using evidence. categories. Recognize and analyze alternative explanations. Pr Students learn the meteorological concepts Communicate procedures, descriptions, otocols of cloud heights, types, and cloud cover and and predictions. learn the ten basic cloud types. Science Concepts Time 10 minutes Earth and Space Science Weather can be described by qualitative Level observations. All Weather changes from day to day and L earning A earning over the seasons. Frequency Weather varies on local, regional, and Daily within one hour of local solar noon global spatial scales. Clouds form by condensation of water In support of ozone and aerosol measure- vapor in the atmosphere. ments ctivities Clouds affect weather and climate. At the time of a satellite overpass The atmosphere has different properties Additional times are welcome. at different altitudes. Water vapor is added to the atmosphere Materials and Tools by evaporation from Earth’s surface and Atmosphere Investigation Data Sheet or transpiration from plants. -
ICA Vol. 1 (1956 Edition)
·wMo o '-" I q Sb 10 c. v. i. J c.. A INTERNATIONAL CLOUD ATLAS Volume I WORLD METEOROLOGICAL ORGANIZATION 1956 c....._/ O,-/ - 1~ L ) I TABLE OF CONTENTS Pages Preface to the 1939 edition . IX Preface to the present edition . xv PART I - CLOUDS CHAPTER I Introduction 1. Definition of a cloud . 3 2. Appearance of clouds . 3 (1) Luminance . 3 (2) Colour .... 4 3. Classification of clouds 5 (1) Genera . 5 (2) Species . 5 (3) Varieties . 5 ( 4) Supplementary features and accessory clouds 6 (5) Mother-clouds . 6 4. Table of classification of clouds . 7 5. Table of abbreviations and symbols of clouds . 8 CHAPTER II Definitions I. Some useful concepts . 9 (1) Height, altitude, vertical extent 9 (2) Etages .... .... 9 2. Observational conditions to which definitions of clouds apply. 10 3. Definitions of clouds 10 (1) Genera . 10 (2) Species . 11 (3) Varieties 14 (4) Supplementary features and accessory clouds 16 CHAPTER III Descriptions of clouds 1. Cirrus . .. 19 2. Cirrocumulus . 21 3. Cirrostratus 23 4. Altocumulus . 25 5. Altostratus . 28 6. Nimbostratus . 30 " IV TABLE OF CONTENTS Pages 7. Stratoculllulus 32 8. Stratus 35 9. Culllulus . 37 10. Culllulonimbus 40 CHAPTER IV Orographic influences 1. Occurrence, structure and shapes of orographic clouds . 43 2. Changes in the shape and structure of clouds due to orographic influences 44 CHAPTER V Clouds as seen from aircraft 1. Special problellls involved . 45 (1) Differences between the observation of clouds frolll aircraft and frolll the earth's surface . 45 (2) Field of vision . 45 (3) Appearance of clouds. 45 (4) Icing . -
Manipulating Marine Stratocumulus Cloud Amount and Albedo: A
Review of “Manipulating marine stratocumulus cloud amount and albedo: a process-modeling study of aerosol-cloud-precipitation interactions in response to injection of cloud condensation nuclei”, by Wang, Rasch, and Feingold Recommendation: Accept subject to some revision Review by Robert Wood, University of Washington Overview: This paper uses large-domain large eddy simulations to explore the sensitivity of marine stratocumulus clouds, under two sets of meteorological conditions and three different background microphysical states, to injections of cloud condensation nuclei (CCN) from ships. The experiments are designed to test a widely-known geoengineering proposal to increase the planetary albedo by increasing the cloud shortwave reflectivity through injections of artificially- generated sea-salt aerosol. The study is very interesting and finds that only for some of the background cloud states (meteorological/microphysical) do the injections significantly increase the albedo. Clouds with the higher concentrations of background CCN typical of moderately polluted marine stratocumulus are barely susceptible to CCN injection. Clouds with low background CCN are typically more susceptible but only when the background state is precipitating. Indeed precipitation suppression appears to be a necessary condition for the CCN injection to increase cloud albedo, but too much drizzle is found to reduce the susceptibility somewhat. This dependence of albedo increase upon precipitation suppression is not solely because precipitating clouds are also those with low CCN and therefore are more susceptible in the Platnick and Twomey sense, since the dry meteorological conditions case has relatively low CCN (55 cm-3 in the unperturbed case) that one would expect to be susceptible. The results are intriguing and certainly worthy of publication in Atmospheric Chemistry and Physics. -
Clouds and Precipitation
Chapter 9 CLOUDS AND PRECIPITATION Fire weather is usually fair weather. Clouds, fog, and precipitation do not predominate during the fire season. The appearance of clouds during the fire season may have good portent or bad. Overcast skies shade the surface and thus temper forest flammability. This is good from the wildfire standpoint, but may preclude the use of prescribed fire for useful purposes. Some clouds develop into full-blown thunderstorms with fire-starting potential and often disastrous effects on fire behavior. The amount of precipitation and its seasonal distribution are important factors in controlling the beginning, ending, and severity of local fire seasons. Prolonged periods with lack of clouds and precipitation set the stage for severe burning conditions by increasing the availability of dead fuel and depleting soil moisture necessary for the normal physiological functions of living plants. Severe burning conditions are not erased easily. Extremely dry forest fuels may undergo superficial moistening by rain in the forenoon, but may dry out quickly and become flammable again during the afternoon. 144 CLOUDS AND PRECIPITATION Clouds consist of minute water droplets, ice crystals, or a mixture of the two in sufficient quantities to make the mass discernible. Some clouds are pretty, others are dull, and some are foreboding. But we need to look beyond these aesthetic qualities. Clouds are visible evidence of atmospheric moisture and atmospheric motion. Those that indicate instability may serve as a warning to the fire-control man. Some produce precipitation and become an ally to the firefighter. We must look into the processes by which clouds are formed and precipitation is produced in order to understand the meaning and portent of clouds as they relate to fire weather. -
Chapter 13 Cloud-Topped Boundary Layers
Boundary Layer Meteorology Chapter 13 Cloud-topped boundary layers Boundary layer clouds ¾ The presence of cloud has a large impact on BL structure. ¾ Clouds that are limited in their vertical extent by the main capping inversion are an intrinsic feature of the cloud-topped BL (CTBL) - they consist mainly of three types: 1) Shallow cumulus (Cu) in the form of fair-weather cumulus (either as random fields or cloud streets); 2) Stratocumulus (Sc); and 3) Stratus (St). ¾ In addition, fog may exist in the lower regions of the BL in the form of radiation fog, frontal fog, advection fog and ice/snow fog. Fog ¾ Fog is defined as cloud in contact with the surface. For the present purposes, we exclude from this definition cloud in contact with hills or mountains. ¾ Over land, fog may form at night as a consequence of radiative cooling of the surface. ¾ Heat is lost from the air radialively and diffused downward into the surface by wind-induced turbulence. If the air near the ground is cooled to its dew-point temperature, condensation occurs, first near the ground and later at higher altitudes. ¾ Initially, the fog is thickest near the surface, with the cloud- water content falling off rapidly with altitude. ¾ If it does not achieve a thickness greater than a few meters by sunrise, it will remain in this state until absorption of sunlight by the surface and by the cloud itself raises the temperature enough to evaporate the cloud. ¾ Thin fog of this kind is not convective, because the cooling occurs from below. ¾ If the fog achieves a thickness greater than 5 or 10 m, a remarkable transition occurs.