Clouds of the Day - Morning, Afternoon, Evening, Thursday, August 3, 2023

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Today began with dense fog with visibility down to 1/4th of a mile.

Fog

Fog

By the middle and late afternoon Cumulus clouds formed. Altocumulus and Altostratus are seen above the Cumulus.

Cumulus mediocris

By evening, Cirrus (high clouds), Altocumulus (middle clouds), and Cumulus fractus (low) clouds dominated the sky as shown in the left photo. The lower right photo shows Altocumulus floccus with Altostratus smeared across the bottom half of the right hand photo below and a small patch of thin Altostratus at the top of the same photo.

Cirrus, Altocumulus, Cumulus fractus

Altocumulus floccus, Altostratus

Photogenic Clouds from Above and Below - Clouds of the Day - Sunday, July 30, 2023

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Satellite images are useful tools for forecasters. It is not just about the pretty pictures, it’s about the details in the images that reveal developing and dissipating storm systems. Meteorologists glean a lot of information from satellite images - much more than you might expect. The images can be compared with computer model forecasts to see how well the models are performing and helps forecasters produce better forecasts than the models alone.

Here is an image from this evening. My location is Cedar Falls, Iowa located in Northeast Iowa next to Waterloo. The Altocumulus/Altostratus/Cumulus cloud pointer locates our general area. The satellite image shows what those cloud types looked like from space.

I have also pointed out many other cloud types on this image. Special note: the cool air boundary in Illinois and Indiana locates the leading edge of cooler/drier air that has spread off the Great Lakes. It is a shallow layer of cooler air and the leading edge acts much like a cold front. Scroll down to the surface map plot to learn more.

Scroll down to see what the clouds looked like from the ground.

notice the milky looking sky over northern Minnesota into canada and across the upper great lakes. It is wildfire smoke from canada that continues to plague parts of the United States. This image is courtesy of NOAA. YOu can link to current GOES satellite imagery from our homepage. Click on the GOES link.

Notice the Cool Air Boundary labeled on the satellite imagery. It is identified by the narrow line of cumulus clouds that has formed along its leading edge. Compare the shape and location of the cloud line with the trof (that is short for trough line) dashed line on the map from Illinois into Indiana to a weak low center Ontario. The shape on the map does exactly not match the satellite. The satellite gives the best location for the trof line because the data on the map is not spaced close enough together to place the trof exactly. The satellite image gives forecasters a better look at the trof and what is going on along it than the surface map.

If you have practiced your station model plotting or have looked at where the data is plotted around the observation locations on the map you know that the temperature and dew point are plotted to the left of the station location. For example Chicago reports a temperature of 76 and a dew point of 55. The cooler air behind the trof has dew points in the 50s. Ahead of the trof dew points are in the 60s.

The trof line is where the leading edge of cooler drier air shows up on the satellite image as line of cumulus clouds. The satellite provides the best look at where the trof is really located. The surface map shows us the weather observations on the ground - wind, temperature, dew point, cloud cover, pressure and pressure changes. Using both sources of information gives us the best picture of the trof location and weather conditions ahead and behind it.

Scroll down to see the clouds over northeast Iowa.

Map plotted using Digital Atmosphere software from www.weathergraphics.com.

Let’s focus in on the clouds over northeastern Iowa. We see them on the satellite image and now from the ground. The photos below were taken at the same time as the satellite image. These clouds were all above 6,500 feet and below 20,000 feet so their name is prefixed by ‘Alto.’ The clouds are heaped so they are cumulus type clouds. Their name is Altocumulus. Most of them have heaped tops which is the giveaway. Knowing whether to name them Altocumulus takes experience. Over time you will gradually learn the difference between how lower Cumulus look when compare to mid-level Altocumulus. These clouds are tricky because they are large enough to look like a lower cloud but our nearby airport was measuring the clouds above 6,500 ft (above 2000 meters) which puts them in the mid-levels. If you look at Altocumulus clouds in other posts here you will not see many that look this large. Altocumulus castellanus can be this large but part of that is due to how low in the mid-levels they form. Clouds closer to the ground look larger than high clouds.

The Beginning and the End - Clouds of the Day - July 28, 2023

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Altocumulus floccus are forming in the mid afternoon on a hot July afternoon. This cloud type will often precede the formation of showers and thunderstorms. On this day these clouds were indicating the formation of updrafts in the mid-levels of the atmosphere. While showers and storms do not always follow you can notice happens when these and other Altocumulus form. You may see thicker cumulus form which grow into cumulus congestus and cumulonimbus (thunderstorms).

The two photos here are of clouds that formed before (above) and after (below) thunderstorms developed and moved through the area. There were severe storm warnings for hail and high winds nearby. While we heard non-stop thunder, the rain was light with only .12 inches recorded. Stronger storms with more rain formed to our northeast and west, all moving southeast.

These mammatus clouds (below) form on the underside of a thunderstorm anvil when downward moving air currents creates protuberances from the base of the anvil. These clouds are not dangerous but they are distinctive and are frequently associated with strong thunderstorms. In this photo he mammatus are obviously in the background with a low level cumulus cloud in the foreground. At the time our winds were calm and there was no rain.

The yellow cast on the mammatus is due to the light from the setting Sun illuminating them. Sunlight includes all colors seen in a rainbow but at sunset or sunrise sunlight travels along a much longer path in the atmosphere than at midday. In this case the yellow and orange colors dominate the color of the light while other colors are filtered out by the Earth’s atmosphere.

…more text will be added.

Its COLD Down Under in Antarctica

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Here is a surface station plot from Antarctica yesterday (July 23, 2023). The temperature is plotted to the upper left of the locator circle or square. If the location is marked by a circle then the observation is augmented by human observers. Stations marked by a square are completely automated.

Notice the temperatures. The warmest readings are near the coast. The coldest readings are in the interior of the continent. The coldest temperature is -112 Fahrenheit. It is warmer near the coast because the stations are nearest water which always moderates temperatures either warmer or colder depending on the season. In winter (it is winter now now in Antarctica) open water would moderate temperatures warmer at nearby weather stations. The continent would be colder. Stations in interior in high mountain valleys or plateaus will be much colder. You can see temperatures of -48, -83, and -85 in the interior with -77 at Amundsen-Scott Station (USA) at the South Pole and -39 closer to the Weddell Sea to its left. Temperatures at two stations near the coast on the lower right are -30 at the USA McMerdo Station and -29 at another human augmented weather station. These stations have ice covered water at the Ross Ice Shelf.

Notice the temperatures that are above freezing along the Antarctica Peninsula at the lower left. Those stations are located near open water.

Map plotted using digital atmosphere software available at www.weathergraphics.com.

Smoke Particles Screening Sunlight - Saturday, July 15, 2023

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Smoke from wild fires returned today obscuring the sky and reducing surface visibility to 5 to 8 miles. The top photo below is looking south at 7:00 p.m. this evening. Clouds and blue sky are visible through the layer of smoke. The second photo is looking west at the setting Sun. More scattered light from the small smoke particles is reaching the ground from that direction so the sky is completely obscured by the smoke. Notice the reddish tint to the sunlight. The is due to the selective scattering of colors in the sunlight away from our field of view. The longer wavelength of red light get through unscathed. The other colors closer to the green, yellow, and blue spectrum are screened out.

How Water Controls Temperature

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The photos below were taken on July 13, 2023 during the late morning. The day started with clear skies but soon solar heating and a humid air destabilized the air mass. The Cumulus clouds show currents of rising air. The moist air condensed cloud droplets to form cumulus clouds which expanded upward throughout the afternoon. Finally a few thunderstorms developed. The photo on the left shows Cumulus cloud bases from almost directly below. The photo on the right shows Cumulus congestus clouds which evolved into thunderstorms.

Cumulus clouds

The top chart below shows a graph of temperature changes on the 13th, 14th, and 15th. A sharp drop in temperature is shown on the first graph when cooler air reached our weather station. The air was flowing out of a thunderstorm as rain cooled air descended to the ground. The cooling was aided by the evaporation of rain drops. Evaporation requires heat so they air cools as the heat evaporates the water. As the air mass aloft cools it becomes more dense and heavier. The heavier air descends, usually with gusty winds flowing out of the leading edge of the storm. Gravity wins! The cooler air mixes with warmer air which warms the cool air and cools the warm air. That is one example of how important water is the life on Earth. As it changes from water vapor to liquid water or snow and ice it regulates global temperatures. As the most important Greenhouse Gas, water vapor cools and warms the planet helping to keep temperatures within boundaries that keep life possible on Earth.

You can see 10-minute observations and the accompanying graphs from our automated weather station on our homepage and in the section about the weather stations and making observations.

Clouds of the Day - Thursday, July 13, 2020 - Caldron of Cumulus

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Summer brings warm humid days and cumulus clouds. Today has been good example. The day started with a clear sky but by 9:30 cumulus clouds began to form. The air mass was humid and as the Sun heated the earth it warmed the air above which began rising. Cloud bases form at the condensation level.

When water vapor condenses it releases heat. The heat is called “latent” because it is stored with the vapor when water evaporates. Heat is required to evaporate water. So when the vapor condenses into water droplets or ice crystals the heat is released into the air. Condensation adds heat to the air - the heat that was needed evaporated the water was released back into the air when it condensed back into cloud droplets.

The evaporation into invisible water vapor, its movement with the wind, and condensation back to water or ice is a key component of the water cycle and global temperature regulation. As water vapor moves with the air the heat is transported without it changing the temperature of the air. The heat is “latent,” and therefore does not change the temperature of the air until it condenses.

Backlit cumulus.

Cumulus congestus

The same Cumulus congestus as above but a few minutes later

Cumulus cloud bases - where condensation occurs

Cumulus mediocris

Cumulus with Cirrus above

Cumulus with Cirrus in the background

Cumulus with Cirrus, Cirrus spissatus, and Cirrus spissatus with ice crystal streamers above

Cumulus with Cirrus and Cirrostratus above

Clouds of the Day - Friday, June 30, 2023 - Altocumulus

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The sky can change quickly in the summer. These clouds appeared during the early evening. They look like pillows lined in rows with denser clouds merged into a single layer. These are Altocumulus - mid-level Cumulus clouds.

The photo below is a closer view of altocumulus. In this photo the rows are not pronounced which indicates the rising motion is more random without distinct wave action. The clouds are created by rising air and the clear areas occur where there is sinking air.

Rows of cumulus clouds in waves are visible in the lower right of this photo. The waves are similar to waves or ripples that form when a rock is thrown into water. The atmosphere often contains waves due to differences in wind direction and wind speed between adjacent layers. They are only visible if clouds form but anyone who has flown can testify that waves occur in clear air because turbulence is felt by the passengers.

The photo below has several different types of mid-level Altocumulus clouds. They are Altocumulus floccus, Altocumulus castellanus, and Altocumulus stratiformis. The stratiformis are in a layer while the others are discrete Altocumulus cells in groups. These forms are also in the photos above.

The sky became more dramatic as the setting Sun reflected off the cloud bases as shown below. These Altocumulus show the remnants of being aligned in rows.

If you enjoy taking cloud photos keep in mind that the best time of a sunny day to take photos is the first hour after sunrise and the last hour before sunset. That is when sunlight is softer often wit;h shades of red or yellow. The time before 10:00 a.m. and after 4:00 p.m. is when the Sun is lower in the horizon and provides interesting shadows that add depth to your photos. The closer you are to sunrise or sunset the more dramatic the photos may become. The hard part is not being able to control the weather or the lighting. And remember, always look behind you for a good shot too.

Clouds of the Day - Thursday, June 29, 2023 - Cirrus Paint a Picture

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After days of smokey skies and haze near the end of Thursday seeing these cirrus was a welcome relief. The first photo below is Cirrus fibratus. The cloud looks like a tangle of filaments made of icy crystals. The filaments look like tangled hair, some in streaks and some in clumps. This is a great example of how cirrus gets its name - hairlike clouds in delicate wispy strands.

Below we see more Cirrus filaments. Ice crystals are falling out of small clumps of ice clouds leaving fall streaks in their wake. Near the bottom of the image we see the only type of Cirrus that may cover the Sun’s disk. They are called Cirrus spissatus and they also often trail fall streaks of ice crystals.

The formation below is unusual in that this combination of clouds is often seen together. It is a combination of straight streaks of Cirrus filaments with wave clouds. A dense patch of either low Cirrocumulus or a small clump of very high Altocumulus is visible just right of the lower left tree. Altostratus or Cirrostratus are visible in the lower right. The low evening Sun angle and low position of the clouds makes it hard to distinguish the cloud type.

Below we see a spectacular display of cloud filaments. On the left they appear to spray out of a single point behind the trees. On the right they look like tufts of hair all thrown together while rising out of the same point. Ice crystals are falling from most of these clouds to create the streaks.

Clouds of the Day - Canadian Wildfire Smoke - Tuesday, June 27, 2023

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Smoke returned to Iowa skies over the weekend as smoke from Canadian Wildfires lowered visibility to 2.5 miles (from our usual 10 miles). The three photos below were taken between 8:00 and 8:15 CDT this evening. The reddish tint to the sunlight is due to the smoke screening out all but the longer wavelength red light. The overall sky was very muted in color and also had a reddish hue.

This morning we could smell the smoke. We could also see haze that was associated with the smoke throughout the afternoon and evening. The diffuse clouds in a line from just above the Sun to the upper right of the photo turned out to be Cirrus floccus (like flocks of wool) that were precipitating ice crystals. Those clouds moved overhead here at 8:45 p.m. and had nearly disappeared as the crystals had turned to vapor in the dry air aloft.

The Aviation Weather Center

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This is the first post in a series about websites that are linked to on the Weather Briefing homepage. The Aviation Weather Center website includes observations, advisories, forecasts, and other information pertaining to aviation. For example, on the AWS homepage click on any Convective Outlooks to read a forecast for the area outlined on the map. There are also forecasts for terminal areas, in route turbulence, and pilot reports. You may link to the AWC from our homepage or click on the image below. The AWC website is a product of NOAA and the National Weather Service.

Note: The image below was valid on the day of this post - it is not updated. You must link to the AWS website homepage for the latest information.

Note 2: There is a beta version of the AWC website here: https://beta.aviationweather.gov/

Click on this image for current information from the Aviation Weather Center. This image is only an example and is not updated.

Clouds of the Day - Monday, June 26, 2023

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The morning began with a layer of stratus (low flat shapeless cloud that covered the sky) that gradually evolved into cumulus clouds as sunshine heated the ground and cooler air aloft overspread the region. This created an unstable situation which caused the cooler air aloft to descend bringing gusty winds to the surface. At the same time low level air in contact with the ground was being heated by the Sun causing it to rise. The result was what you see here. By late afternoon and early evening clouds took on the look of small showers that were rooted mainly in the mid-levels of the atmosphere. We received a trace of rain from sprinkles. That was after much needed 1.08 inches of rain fell over the weekend.

Cumulus congestus

Cumulus congestus

Cumulus congestus top with a large bird silhouetted against the cloud

Base of cumulus congestus

Altocumulus floccus and cumulonimbogenitus (a developing cumulonimbus)

The photo on the left above shows the base of the cloud that is featured in the first three photo above. The photo on the right above is a mid-level cloud formation which is forming in rising motion at that level. This area of clouds eventually developed into a cumulus congestus (not quite as big as the first three clouds beginning at the top of this post.

Cumulus congestus top with the Moon visible above

The photo above shows the top of the cloud in the photo below.

cumulonimbogenitus (A developing cumulonimbus)

This developing cloud never got much bigger than this but I am sure sprinkles fell from it to our southeast.

Clouds of the Day - Sunday, June 18, 2023 - The Cap Cloud

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The photos below show a cloud capping a developing Cumulonimbus calvus. The cap cloud is a thin smooth cloud that creates a “cap” over the top of the building cloud below. The cap is a layer of moist air being lifted by the rapidly rising air. The lift has cooled the layer to its condensation level. This cloud has moved past the Cumulus congestus stage and is showing signs of losing its upward motion. The fact that the cap cloud quickly dissipates may indicate that the lifting is weakening causing the cooling of the cloud top to slow with evaporation of the cap to take over. From the first to the second photo the cloud top is becoming more rounded with fewer protuberances, which may indicate slowing updrafts.

Notice the bird silhouetted against the cloud in the lower photo. The photos were taken less than a minute apart. The upper photo was taken first.

Clouds of the Day - Thursday, June 15, 2023 - More Smoke

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Smoke covers much of the northern two-thirds of the Eastern United States. It shows up very well on the satellite images below. The top photo shows the smooth gray to brown smoke. The sky over these areas looks hazy and in areas where the smoke is at ground level visibility is reduced. The second photo shows the Upper Midwest with a widespread layers of smoke covering the region.

Satellite images courtesy of NOAA/NESDIS/STAR. Click HERE to go to the website.

The chart below shows surface wind streamlines this morning. The arrows indicate a snapshot of the wind direction. Notice the large expanse of no streamlines from the central and southern Great Plains to the Upper Ohio Valley. Look at the surface observations in that region. Most of the weather stations indicate no wind (The station circle does not have a ‘flag’ showing the wind speed and direction.). Also notice the streamlines pointing away from southeastern Canada into the ‘dead zone’ of no wind. Smoke has been collecting in that area.

This chart is plotted by Digital Atmosphere Software available from www.weathergraphics.com. The title in the lower left is placed by Weather Briefing, LC.

Clouds of the Day - Thursday, June 8, 2023 - More Smoke

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The GOES 16 visible satellite image from this afternoon at 20:36Z is showing more smoke over the Upper Midwest. There are several bands of smoke visible. The smoke is not as dense or reducing visibility like has been experienced in the northeastern U.S. The smoke here is aloft - not near the ground. It has been creating a smooth milky sky. This image is courtesy of NOAA/NESDIS STAR GOES EAST. The text is added by Weather Briefing, LC.

You will also notice thunderstorms over North Dakota, South Dakota and south into Nebraska. The storms in North Dakota are sporting large anvils while the storms in South Dakota and Nebraska have much smaller anvils. Anvils are also visible in northeastern Kansas to Arkansas. Look closely and you can see the shadows cast on the ground by the anvils. Cumulus cloud fields are over the Plains and also in southern Indiana through Kentucky to Tennessee. The Cumulus fields indicate low level instability caused by solar heating. The thunderstorms indicate areas of much deeper instability caused by other factors that are aided by solar heating.

Clouds of the Day - Thursday, June 8, 2023 - Going Vertical

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Below are a few photos from June 4th. The principle cloud type is Cumulus and the species is congestus which makes the name Cumulus congestus. The last photo is Cumulus fractus - a “fractured” cumulus cloud. Before the photo was taken the clouds was a Cumulus congestus but it quickly evaporated leaving the debris in the upper center-left of the photo. Learning cloud names is easier if you can take the time to practice. It is all done through repetition.

What’s in a name? If someone asks you for the name of the clouds in the photos below, just say Cumulus, and you would be correct. Cumulus is one of ten principle cloud types. The principle cloud type (also called genus) describes the altitude and form of the cloud. If you want to describe the cloud further add a second name - the species. Species describes the size, shape, and form of the cloud. The Weather Briefing cloud chart includes the genus and species names. If you go one step further the cloud variety name can be added. It describes the cloud layer thickness, the arrangement of cloud elements, or the presence of multiple layers. See the supplements to the cloud chart on our website for more information.

Clouds of the Day - Wednesday, May 31, 2023

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The Clouds of the Day today are courtesy of a weak upper level system that as shown up as a patch of Cirrus, Cirrostratus, Altostratus, and Altocumulus which is shown on the two images below. There are several areas of Cumulus/Cumulonimbus (showers and thundershowers) over the Upper Midwest this morning near the Iowa Minnesota border, in the Dakotas, and over Kansas, Missouri, and Illinois

IMage courtesy of NOAA/NESDIS/STAR. Find more images using the link to GOES Satellite images on the Weather Briefing home page. The text added to the photo is by Weather Briefing, LC.

Nationally there are showers and thundershowers over the Southern Plains back to the crest of the Southern Rockies and also over the southeastern U.S. and along the East Coast and the eastern Gulf of Mexico.

IMage courtesy of NOAA/NESDIS/STAR. Find more images using the link to GOES Satellite images on the Weather Briefing home page.

Identifying clouds can be a bit tricky because while we like to categorize clouds into specific groups, they don’t always behave that way. The first photo below shows clouds that look like Cirrus and Altostratus. I categorize these clouds as Cirrostratus because they do not completely hide the Sun’s disk - but it’s close. You can see thicker portions of these clouds that might hide the Sun but so far that has not been the case. So, all things considered at least parts of these clouds could be labeled Altostratus. They would be on the high side of the middle layer of the atmosphere in a region where we can find both Cirrus and Altostratus.

Photo by Craig Johnson 5-31-2023.Copyright 2023. All rights reserved.

The next two photos show Virga (precipitation aloft not reaching the ground) which are also called Fall Streaks. They are ice crystals falling from Cirrus. When overhead they can be hard to see but with the benefit of the side view we see them for what they are.

Photo by Craig Johnson 5-31-2023.Copyright 2023. All rights reserved.

Photo by Craig Johnson 5-31-2023.Copyright 2023. All rights reserved.

Below is an interesting formation. This view is looking southeast. Cirrus dominates the lower half of the photo but the thicker cloud layer in the top half has the characteristics of a dissipating anvil from an old thundershower.

The regional satellite image at the top of this post shows this dense cloud to have a similar shape to the top of a thundershower. Without continuity it is difficult to say what it is but the shape is recognizable. The atmosphere is well organized even though it may sometimes seem chaotic. Many cloud shapes appear at different heights and sizes because the overall system is orderly. Many features that occur in the small scale are also evident in the large global scale. For example, rotating thunderstorms have similar characteristics to larger low pressure systems. These storms may appear to be random but they are not.

Photo by Craig Johnson 5-31-2023.Copyright 2023. All rights reserved.

Clouds of the Day - Tuesday, May 30, 2023