by Photography World Editor & Photographer Mina Thevenin
Clouds can roll in upon an otherwise quiet landscape and color the previously bright and sun-warmed crags of boulders or forest flora with deep and mysterious unknowns that seem to move and moan, and all too quickly the familiar landscapes lose their quiet in the suddenly changing shades and shadows of the shape-shifters we call clouds.
Quiet, without a sound to call its own, the cloud is a most beautiful part of nature. Clouds speak their own language. It is one of shapes, of color, movement, stillness and dissipation. What is our relationship to these odd and magnificent beauties? We can be inspired and awed, and sometimes even frightened or grateful for their might. Born from sun, dust, water and wind, the cloud speaks to us in a language of nature and wonder, gifting us with a Photography World of clouds.
WHEN CLOUDS KISS THE EARTH
Fog & Mist. The lowest clouds
O to 6,500 feet/1981.2 meters
STRATUS CLOUD “FLAT GRAY Sheer OR BLANKET FLANNEL”
Low-lying clouds consist of billions and billions of water-droplets. The lowest cloud type is fog. Early mornings during the autumn season may produce fog in low-lying areas of land and water ways. In the fall season as night temperatures drop and the land or waterscape stays warm from the day’s sun, a person may wake up in the morning to find a blanket of fog upon the earth.
Morning fog upon the Ohio River in the fall is an example of a stratus cloud. In this photograph (above) a Great Blue Heron flies as a Cormorant watches from the log in the water. Autumn colored trees and houses can be seen on the Indiana shore.
Fog is a type of cloud called stratus. (Stratus means flattened or spread-out in Latin.) When the air is cooler than or equal to the ground’s surface temperature, and there is high humidity, the level of water droplets in the air becomes so overly saturated that dew forms (dew point) on the ground. Tiny water drops cover everything. This type of fog is known as radiation fog .
Radiation fog falls “like dew” upon the spider’s web and “burns off” as the sun rises and heats the morning. (Image left.)
When the air is warm and moist and it blows over colder surface temperatures it is called advection fog– San Francisco Bay and its Golden Gate Bridge or fog upon an ocean or snowy land mass is an example of advection fog.
Mist is the denser version of fog and it reduces visibility much more than fog. Mist also often has a fine spray of rain that it produces; this is called mist (fig. 4-1 & 4-2).
Both fog and mist often “burn off” and disappear when the sun heats up by mid morning and evaporates the water-droplets contained therein the fog and mist.
Click on any image to view photography as a slide show.(Slide mouse over image for copyright photograph details.) Some highlighted words are links.
Fig. 4-1 (above) Volcano mist photographed in early morning on the rim of Mount Liamuiga, St. Kitts Island in the Caribbean. Elevation 3,793 feet/1,156 meters.
Rainforest of Mount Liamuiga, St Kitts Island. (fig 4-2)
PHOTOGRAPHY CHALLENGES OF FOG & MIST
Hiking through a tropical rainforest to the rim of Mount Liamuiga (fig.4-1), the inactive volcano on the Caribbean island of St. Kitts, the cloud layer of mist as a stratus cloud began to be present at 1,000 feet (fig. 4-2). Photography was difficult because the light “mist” clouded and caused heavy condensation droplets on the camera lens.
Because mist and fog diffuse light, the photographic composition is often dimly lit and soft. Unless the forward part of the subject composition is near the photographer, there is less contrast produced. Color saturation is also less. Attempting to adjust for contrast, color, or light in the post processing of fog/mist images often destroys the quality of pixels and neighboring cells (fig. 5). Maintaining a copy of the original image “untouched” is often the final product anyway.
THE TECHNICAL ASPECTS OF CLOUDS
The Troposphere Layer of Our Atmosphere-
50 PERCENT of Our Weather occurs in the troposphere layer
According to the American Federal Aviation Administration (FAA) and their chapter on weather theory regarding earth’s five layers of atmospheres:
The first layer, known as the troposphere, extends from sea level up to 20,000 feet (8 km) over the northern and southern poles and up to 48,000 feet (14.5 km) over the equatorial regions. The vast majority of weather, clouds, storms, and temperature variances occur within this first layer of the atmosphere. Inside the troposphere, the temperature decreases at a rate of about 2 °Celsius (C) [35.6 degrees Fahrenheit] every 1,000 feet of altitude gain, and the pressure decreases at a rate of about one inch per 1,000 feet of altitude gain.(1)
The Earth’s atmosphere is constantly in motion and adjusts to maintain an equilibrium. There are numerous factors involved that affect the low level cloud formations. The Earth’s temperature is affected by the sun. As heat rises it meats the cooler air levels of the troposphere and depending on the level of humidity in the air (barometric pressure), based on topographic elevation (sea level to mountains), latitude/longitude, equator, North & South Poles, seasonal changes, the water vapor attaches to dust particles in the air. Cold air cannot support the weight of the growing numbers of water droplets so as the vapor becomes dense (heavy) with water droplets, it sinks to lower altitude levels nearer the Earth. What results are clouds, which form from billions and billions of water droplets clinging together en masse.
Clouds form and move “across the sky” (through the troposphere layer of atmosphere) in belts of elliptical and circular wind currents. What influences wind currents? The Earth’s wind currents are influenced by the force of the Earth’s rotation, called Coriolis. Seasonal changes, topography differences (continents and oceans), and other factors such as frictional forces caused by the topography of the Earth’s surface which modify the movement of the air in the atmosphere also affect wind currents.
THE OTHER LOW CLOUDS
0 to 6,500 feet/1.9812 meters from Earth
Cumulus “animal shapes”
CUMULONIMBUS Storm Clouds Born in Low Cloud Level
Stratocumulus “bumpy sheets of gray”
Just like stratus clouds, cumulus clouds are also made of billions and billions of water droplets. In warmer months when the heat of the sun combines with wind currents, the ever changing fanciful shapes of the cumulus entertain cloud-lovers with the developing and shifting puffs and ballooning creations of whimsical elephants, dogs and other imaginings (fig. 6).
Sometimes, though, the boiling updrafts and summer heat combine to mushroom the cumulus clouds into cauliflower-shaped clouds and thunderstorms may develop: cumulonimbus. Nimbus means rain in Latin. Cumulonimbus clouds that develop a sheer anvil-shaped top will be pushed in the same direction of the wind. With quick moving updrafts, they can reach amazing heights to 36,000 feet (almost seven miles/11 kilometers) within an hour! When these are high altitude cloud fronts with lots of movement, primarily wind shears and instability, they are called supercells (fig.7). At that height, the tall anvil-shaped clouds form ice crystals and thunderstorms are likely to develop. Ice crystals that reach Earth are called hail. Lightning, squalls (strong winds) and sometimes funnel clouds or tornadoes develop from such thunderstorms.
In winter, virtually the same clouds as spring and summer, but now speaking in much colder temperatures (usually below 32 degrees Fahrenheit/0 Celsius) produce, not rain, but snow or sometimes ice storms.
(Fig. 6, below) Early Colorado spring with snow-covered Rocky Mountains are dappled in light by cumulus beauties capped with higher altocumulus.
SUNSET SUPERCELLS. (Fig. 7, above ) Summer sunset- two supercells, stacked tall from the summer heat and warm updrafts, collide over the Caribbean island of Nevis. Rain can be seen on the left of the image, while the right side of the photograph depicts sunset colors. Note the large bottom rotation of the right supercell. Wide angle photograph taken from two miles or 3.2 kilometers away.
Usually one type of cloud is associated with extreme-weather: the mature cumulonimbus.
When warmer updrafts push the cloud higher into colder air, the water-droplets bump and bounce against the cloud’s higher altitude ice crystals (the top of the cloud’s anvil-shape). An electrical charge between the cloud’s bottom and top develops. A lightning flash is the result and electricity is discharged within the cloud. Nearly half of all lightning occurs within the storm cloud (1). When the lightning flash leaves the cloud it may take one or more of several paths of least resistance: cloud-to-cloud, cloud-to-ground, ground-to-cloud lightning flashes, cloud to clear-air, and the rare- clear-air lightning which is triggered by a storm not on location of the lightning strike.
Sheet lightning is the internal cloud electrical flashes without the dramatic lightning strike or bolt; sheet lightning also occurs cloud-to-cloud. Lightning can have spider (fig.8, right, Photograph of the Washington Monument with spider lightning and storm in the background) discharges from the electrical strike. Forked lightning occurs when there is a significantly brighter stoke discharged from the cumulonimbus storm cloud, with a number of lesser “forked” bolts running jagged off the main brighter strike. Heat lightning occurs when lightning flashes are observed on or above the horizon but thunder cannot be heard because the observer is too far away from the storm for the thunder sound to travel- and be heard.
According to the Severe Weather Storm Laboratory (2), a massive lightning strike can be several hundred million to one billion volts and contain millions of watts (fig. 9). Lightning heats up the air from its seasonal atmospheric temperature to a quick and sizzling 18,000 degrees Fahrenheit to 60,000 degrees Fahrenheit within less than a second. Because the air does not have time to compensate for the nearly instant temperature increase, a sound wave reaction pops and echoes: called thunder(3). Scientists also know that thunder vibrations result when particles in the air are disturbed by an electrical path moving through it; these vibrations are audibly heard by the ear and are called “thunder”.
Photographer Linda Covey captured a rare Arizona desert sunset storm that included both the lightning strike and a dust storm. Note the lightning strike into the radio tower in the right of the image.
FROM THE SKY WE LOOK DOWN AT THE TOP OF CLOUDS & WE MEET THEM EYE-TO-EYE
The light rays coming down, around, or from the top of clouds are called crepuscular rays. When light from the sun is reflected and bounced off particles in the air, i.e. dust, the beams of light appear to radiate in a fan shape. This is an illusion! Crepuscular rays are actually parallel rays and they only appear by perspective to be non-parallel, much like how a “pair” of railroad tracks appears to merge into a single line on the horizon. This is a perspective optical illusion. Notice the crepuscular rays on previous images under, “FROM THE SKY WE LOOK DOWN AT THE TOP OF CLOUDS & WE MEET THEM EYE-TO-EYE”. The rays are parallel and do not have this perspective optical illusion that the viewer experiences from the ground looking up at crepuscular.
6,500-23,000 feet (1.2 miles-4.2 miles)/ 2,000-7,000 m
The “Alto” & Lenticular Clouds
Any cloud with “alto” attached to its name is a mid-level cloud. Middle layer clouds are approximately 6,500 to 23,000 feet(1.23 miles to 4.35 miles)/ 2-7 kilometers from Earth: Alto-cumulus, Alto-stratus, and Lenticular.
Altus in Latin means high. Altocumulus means high & heaped (mass) clouds. Mid-level cloud forms when there is a conglomeration of super-cooled water droplets of -10 Celsius/14 Fahrenheit. Like all clouds, their size and shape depends upon water droplet “count”, temperatures and wind directions. These clouds generally appear in sheets of “lumps”, rolls, or single clouds- colors are white or gray, and undersides may be a darker gray. These middle clouds do not produce rain, but they can be an indicator of rainy weather in the forecast (within 12 to 48 hours). (4)
Lenticular clouds are associated with clouds that form near or above mountains. Because of strong winter and spring wind currents, the lenticular clouds appear like stacked pancakes, cork screws or plates: sometimes they even look like flying saucers! Often they appear to be stationary, but aviation experts know otherwise, that lenticular cloud formations indicate very turbulent conditions. Note the previous photograph Sunset Supercells– does the storm cloud on the right of that image show a lenticular cloud?
Clouds whose base begins above 3.728 miles/6 km
Cirrus, Cirrostratus, Cirrocumulus
The high clouds may be miles high at three to seven and a half miles in the high haze of cirrostratus or patchy “mackerel sky” of cirrocumulus, but neither are a match for the beautiful and delicate angel wing wisps and feathers of high altitude cirrus. In Latin, cirrus means wisp or curl. Though maybe, the language of the cirrocumulus is just as interesting as cirrus, because according to an article on Cirrocumulus, by Windows to the Universe,
“Cirrocumulus clouds are the same size or smaller than the width of your littlest finger when you hold up your hand at arm’s length.”
Highest & Rare Mesosphere Clouds
The language of clouds in the high 50 mile layer of Mesosphere, are summertime “night” clouds— seen as silvery blue wisps or thin bands. They are visible with twilight in the sky. In the photograph, ice crystal clouds are illuminated by the sun because their altitude is so high. (5)
The Photography World article,
A PHOTOGRAPHY WORLD OF CLOUDS As Seen From Earth & Sky: The Language of Clouds.
This article was inspired by the editor’s fascination with cumulus clouds since childhood and the book: Weather World: Photographing the Global Spectacle, by Gordon Higgins in Association with the Met Office. A David & Charles Book. 2007.
(1) Weather Theory, Chapter Two. Federal Aviation Administration. PDF
(2) “Temperature of a Lightning Bolt” The Physics Fact Book. WEBSITE
(3) “What is Thunder?” Science Made Simple. WEBSITE
(4) “Altocumulus,” Weather Facts. Weather Online United Kingdom. WEBSITE
(5) About NLCs, Polar Mesospheric Clouds. Atmospheric Optics. WEBSITE