DOCSLIB.ORG

Cumulus Cloud (Cu)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Cumulus Cloud (Cu) CLOUD Cumulus(Cu) Cumulonimbus(Cb) Stratus(St) Stratocumulus(Sc) Nimbostratus(Ns) Altostratus(As) Altocumulus(Ac) Cirrus(Ci) Cirrostratus(Cs) Cirrocumulus(Cc) Cumulus Cloud (Cu) Cumulus cloud takes on a variety of shapes, but most often it looks like a piece of floating cotton with sharp outlines and a flat base. The base appears white to light gray, and on a humid day, may be only 1000m (3300ft) above the ground and a kilometer or so wide. The top of the cloud-often in the form of rounded tower-denotes the limit of rising air and is usually not very high. These clouds can be distinguished from stratocumulus usually occur in groups or patches. Also, the cumulus has a done or tower-shaped top as opposed to the generally flat tops of the stratocumulus. Cumulus cloud that show only slight vertical growth are called cumulus humilis and are associated with fair-weather; therefore, we call these clouds “fair-weather cumulus”. Ragged-edge cumulus clouds that are smaller than cumulus humilis and scattered across the sky are called cumulus fractus. backback Cumulonimbus Cloud (Cb) Cumulonimbus is one kind of cloud with vertical development. It develops from cumulus and its base is around 600 meters above the land surface and is dark. Its top may extend up to tropopause, over 12,000 meters. Matter constitutes the cumulonimbus at the lower(warmer) part are large droplets, ice crystals at the top and droplets、ice crystals both at the middle. The surface of cumulonimbus is both flat at the top and bottom and is fibrous at the top edges. Phenomena come with strong cumulonimbus are lighting、 thunder、shower、violent tornadoes. backback Stratus Cloud (St) Stratus is a uniform grayish cloud that often covers the entire sky. It resembles a fog that does not reach the ground. Actually, when a thick fog “lifts,” the resulting cloud is a deck of low stratus. Normally, no precipitation falls from the stratus, but sometimes it is accompanied by a light mist or drizzle. This cloud commonly occurs over Pacific and Atlantic coastal waters in summer. A thick layer of stratus might be confused with nimbostratus, but observing the low base of stratus cloud and remembering that light-to- moderate precipitation occurs with nimbostratus can make the distinction between them. Moreover, stratus often has a more uniform base than does nimbostratus. Also, a deck of stratus may be confused with a layer of altostratus. However, if you remember that stratus are lower and darker gray and that the sum normally appears “watery” through altostratus, the distinction can be made. backback Stratocumulus Cloud (Sc) Stratocumulus clouds generally appear as a low, lumpy layer of clouds, the spreading remains of much larger cumulonimbus clouds. They range in color from dark gray to light gray and can appear in rows, patches, or as rounded masses with breaks of clear sky in between rain or snow rarely fall from these clouds and they are larger than altocumulus in appearance (about the size of a clenched fist at arms length - altocumulus are about the size of a thumbnail). backback Nimbostratus Cloud (Ns) The nimbostratus is a dark gray wet-looking cloudy layer associated with more or less continuously of this precipitation is usually light or moderate. It is never of the heavy showery variety. The base of the nimbostratus cloud is normally impossible to identify clearly and its top may be over 3000m higher. Nimbostratus is easily confused with the altostratus. Thin nimbostratus is usually darker gray than thick altostratus and you normally cannot see the sun or moon through a layer of nimbostratus. Visibility below a nimbostratus cloud deck is usually quite poor because the rain will evaporate and mix with the air in the region. backback Altostratus Cloud (As) The altostratus is a gray or blue-gray cloud composed of ice crystals and water droplets. Altostratus clouds often cover the entire sky across an area that extends over many hundreds of square kilometers. In the thinner section of the cloud, the sun （or moon）may be dimly visible as a round disk, as if the sun were shining through ground glass. Thick cirrostratus clouds are occasionally confused with thin altostratus clouds. The face that halos only occur with cirri- form clouds also helps one distinguish them. Another way to separate the two is to look at the ground for shadows. Altostratus clouds often form ahead of storms having widespread and relatively continuous precipitation. If precipitation falls from an altostratus, its base usually lowers. If the precipitation reaches the ground, the cloud is then classified as nimbostratus. backback Altocumulus Cloud (Ac) Altocumulus clouds are middle clouds that are composed mostly of water droplets and are rarely more than 1 km thick. They appear as gray, puffy masses, sometimes rolled out in parallel waves or bands. Usually, one part of the cloud is darker than another, which helps to separate it from the higher cirrocumulus. Also, the individual puffs of the altocumulus appear larger than those of the cirrocumulus. backback Cirrus Cloud (Ci) The appearances of the cirrus are very special. They look like a feathery patch with a faint wisp of a tail at one end. Cirrus clouds usually move across the sky from west to east, indicating the prevailing winds at their elevation, and they generally point to fair, pleasant weather. backback Cirrostratus Cloud(Cs) The thin, sheet-like, high-level clouds that often cover the entire sky are cirrostratus, which are so thin that the sun and moon can be clearly seen through them. The ice crystals in these clouds refract the light passing through them and will often produce a halo. In fact, the veil of cirrostratus may be so thin that a halo is the only clue to its presence. Thick cirrostratus clouds give the sky a glary white appearance and frequently form ahead of an advancing storm hence, they can be used to predict rain or snow within 12 to 24 hours, especially if they are followed by middle-type clouds. backback Cirrocumulus Cloud(Cc) Cirrocumulus consists of pure-ice sometimes with strongly frozen liquid water. It collects of the small water drops in thin cloud mass, appearance dapples or ripples, white and no shadow, cloud sheet mix or isolate at all. Whole of them fall straight, regulation into rank. Often they change from cirrus and cirrostratus also disperses from altostratus. backback.
Load more

Recommended publications
  • Contrail-Cirrus and Their Potential for Regional Climate Change
    Contrail-Cirrus and Their Potential for Regional Climate Change Kenneth Sassen Department of Meteorology, University of Utah, Salt Lake City, Utah ABSTRACT After reviewing the indirect evidence for the regional climatic impact of contrail-generated cirrus clouds (contrail- cirrus), the author presents a variety of new measurements indicating the nature and scope of the problem. The assess- ment concentrates on polarization lidar and radiometric observations of persisting contrails from Salt Lake City, Utah, where an extended Project First ISCCP (International Satellite Cloud Climatology Program) Regional Experiment (FIRE) cirrus cloud dataset from the Facility for Atmospheric Remote Sensing has captured new information in a geographical area previously identified as being affected by relatively heavy air traffic. The following contrail properties are consid- ered: hourly and monthly frequency of occurrence; height, temperature, and relative humidity statistics; visible and in- frared radiative impacts; and microphysical content evaluated from in situ data and contrail optical phenomenon such as halos and coronas. Also presented are high-resolution lidar images of contrails from the recent SUCCESS experiment, and the results of an initial attempt to numerically simulate the radiative effects of an observed contrail. The evidence indicates that the direct radiative effects of contrails display the potential for regional climate change at many midlati- tude locations, even though the sign of the climatic impact may be uncertain. However, new information suggests that the unusually small particles typical of many persisting contrails may favor the albedo cooling over the greenhouse warming effect, depending on such factors as the geographic distribution and patterns in day versus night aircraft usage.
    [Show full text]
  • 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).
    [Show full text]
  • Touching the Clouds Activity Guide
    Touching the Clouds Activity Guide Purpose Provide a mental representation of each cloud type Create a tactile cloud identification chart Overview Individuals will construct and touch a tactile model of common types of clouds to learn how to describe the clouds based on their shape and texture. They will compare their descriptions with the standard classifications using the cloud types identified in the GLOBE Clouds Protocol. Time: 45 minutes to 1 ½ hours, depending on individual’s age Level: All Materials (per person) One large sheet of cardstock (18” x 12”) Tape One set of Braille labels for each cloud type and/or markers One small feather A layered piece of blanket or soft fabric (eight 1’ X 1” pieces) Cotton balls of varied sizes One tissue Organza or a similar material, cut into pieces, one layered 1” x 1” piece Pillow stuffing, one 1” x 1” piece A tsp of sand Three paper clips Liquid glue Scissors Baby Wipes Preparation Use tape to divide the large cardstock sheet in four sections: one for the cloud title at the top and three for the altitudes: using a portrait layout, place three pieces of tape horizontally, from side to side of the sheet. 1. 1” off the upper edge of the sheet 2. 8” off the upper edge of the sheet 1 Steps What to do and how to do it: Making A Tactile Cloud Identification Chart 1. Discuss that clouds come in three basic shapes: cirrus, stratus and cumulus. a. Feel of the 4” feather and describe it; discuss that these wispy clouds are high in the sky and are named cirrus.
    [Show full text]
  • 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 ...................................................................................................................................
    [Show full text]
  • Types of Cloud with Example
    Types Of Cloud With Example Is Gerrard always freeze-dried and glarier when rake some tentacle very agreeably and alright? Is Rock always chemicallyspavined and while elementary toyless Yehudi when lopingreshape some that legislature mucuses. very evilly and inquisitively? Bronson still solidifying This community why data stored on a pepper cloud platform is generally thought of as reserve from most hazards. In cloud types with example of service model and private cloud computing might be adverse for sharing a massive global network to maximize profitability by. There are typically grouped as with redundancies can house on topics such blog, types of cloud types with example of an example of customization with regular upgrades and types of new. This filth where Cloud Computing has face to protect rescue! Please enable more resources with cloud types example of hybrid cloud types of multiple cloud function as you choose? What types of cloud example images are cloud types with example of fog will benefit of the example, with us include popular seo blog focuses on. Pushing email off into the cloud makes it supremely convenient for billboard people, constantly on land move. This type my Cloud Computing is designed to address the needs of a specific change, like a business call an industry. Every toss of cloud has huge picture, but some of them right not clear or appropriate for payment term. Spreading cumulonimbus clouds may also deliver to the formation of nimbostratus. Within the traditional hosting space, services are either dedicated or shared. These three clouds can be described as featureless blanket cloud layers.
    [Show full text]
  • Direccion De Personal Aeronautico Dpto. De
    DIRECCION DE PERSONAL AERONAUTICO 26/09/2021 MTC DPTO. DE INSTRUCCION OGMS/DINF PREGUNTAS Y OPCIONES POR TEMA 14:03 Pag: 1 TEMA: 0626 ATP-RTC - Meteorology and Weather Services - Chap.8 COD_PREG: PREGUNTA: RPTA: PREG20098166 What is indicated on the Weather Depiction Chart by a continuous smooth C (9299) line enclosing a hatched geographic area? OPCION A: The entire area has ceilings less than 1,000 feet and/or visibility less than 3 miles OPCION B: More than 50 percent of the area enclosed by the smooth line is predicted to have IFR conditions OPCION C: Reporting stations within the enclosed area are all showing IFR conditions at the time of the report OPCION D: PREG20098167 The horizontal wind shear, critical for turbulence (moderate or greater) per B (9701) 150 miles is OPCION A: 18 knots or less OPCION B: greater than 18 knots OPCION C: not a factor, only vertical shear is a factor OPCION D: PREG20098168 A severe thunderstorm is one in which he surface wind is A (9706) OPCION A: 50 knots or greater and/or surface hail is 3/4 inch or more in diameter. OPCION B: 55 knots or greater and/or surface hail is 1/2 inch or more in diameter. OPCION C: 45 knots or greater and/or surface hail is 1 inch or more in diameter. OPCION D: PREG20098169 A squall is a sudden increase of at least 16 knots in average wind speed to a B (9708) sustained speed of OPCION A: 24 knots or more for at least 1 minute OPCION B: 22 knots or more for at least 1 minute OPCION C: 20 knots or more for at least 1 minute OPCION D: PREG20098170 A calm wind that is forecast, in the international Terminal Aerodrome B (9709) Forecast (TAF) is encoded as OPCION A: VRB00KT OPCION B: 00000KT OPCION C: 00003KT OPCION D: PREG20098171 In the International Terminal Aerodrome Forecast (TAF), a variable wind C (9710) direction is noted by "VRB" where the three digit direction usually appears.
    [Show full text]
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • 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.
    [Show full text]
  • International Atlas of Clouds and of States of the Sky
    INTERNATIONAL METEOROLOGICAL COMMITTEE COMMISSION FOR THE STUDY OF CLOUDS International Atlas of Clouds and of States of the Sky ABRIDGED EDITION FOR THE USE OF OBSERVERS PARIS Office National Meteorologique, Rue de I'Universite, 176 193O International Atlas of Clouds and of States of the Sky THIS WORK FOR THE USE OF OBSERVERS CONSISTS OF : 1. This volume of text. 2. An album of 41 plates. It is an abreviation of the complete work : The International Atlas of Clouds and of States of the Sky. It is published thanks to the generosity of The Paxtot Institute of Catalonia. INTERNATIONAL METEOROLOGICAL COMMITTEE COMMISSION FOR THE STUDY OF CLOUDS International Atlas of Clouds and of States of the Sky ABRIDGED EDITION FOR THE USE OF OBSERVERS Kon. Nad. Metoor. Intl. De Bilt PARIS Office National Meteorologique. Rue de I'Universite. 176 193O In memory of our Friend A. DE QUERVAIN Member of the International Commluion for the Study of Cloudt INTRODUCTION Since 1922 the International Commission for the Study of Clouds has been engaged in studying the classification of clouds for a new International Atlas. The complete work will appear shortly, and in it will be found a history of the undertaking. This atlas is only a summary of the complete work, and is intended for the use of observers. The necessity for it was realised by the Inter- national Conference of Directors, in order to elucidate the new inter- national cloud code; this is based on the idea of the state of the sky, but observers should be able to use it without difficulty for the separate analysis of low, middle, and high clouds.
    [Show full text]
  • 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.
    [Show full text]
  • Types of Clouds
    Types of Clouds What’s the Weather? Cirrus, Cirrocumulus and Cirrostratus (high 5000-16,000 m) . thin and often wispy . composed of ice crystals that originate from the freezing of supercooled water droplets. Generally occur in fair weather and point in the direction of air movement at their elevation. Cirrus . They are made of ice crystals and have long, thin, wispy streamers. Cirrus clouds are usually white and predict fair weather. cirrus cirrus cirrus cirrus cirrus cirrus Cirrocumulus . They are small rounded puffs that usually appear in long rows. Cirrocumulus are usually white, but sometimes appear gray. Cirrocumulus are usually seen in the winter time and mean that there will be fair, but cold weather. Cirrostratus . Sheetlike thin clouds that usually cover the entire sky. Cirrostratus clouds usually come 12-24 hours before a rain or snow storm. Altocumulus and Altostratus (middle 2,000 to 7, 000 m) . Middle clouds are made of ice crystals and water droplets. The base of a middle cloud above the surface can be anywhere from 2000-8000m in the tropics to 2000-4000m in the polar regions. An Altocumulus . They are grayish-white with one part of the cloud darker than the other. Usually form in groups. If you see altocumulus clouds on a warm sticky morning, then expect thunderstorms by late afternoon. Altostratus . An altostratus cloud usually covers the whole sky. The cloud looks gray or blue-gray. Usually forms ahead of storms that have a lot of rain or snow. Sometimes, rain will fall from an altostratus cloud. If the rain hits the ground, then the cloud is called a nimbostratus cloud.
    [Show full text]