Clouds of the Day - Thursday, May 21, 2020

Stratocumulus

Stratocumulus

Cumulus and Stratocumulus

Clouds of the Day - Wednesday, May 20. 2020

Stratocumulus

Clouds of the Day - Tuesday, May 19, 2020

A departing upper low pressure continues to spin stratus overhead but there were some differences from the past couple of days. A few breaks in the overcast gave a fleeting view of blue sky. There also was a mixture of stratus and cumulus type clouds instead of just stratus.

Stratus, stratocumulus (dark low cloud lower center and right), and Altocumulus (upper left).

Stratocumulus (left) and stratus (upper center to lower right).

Cumulus scattered through most of this photo with Stratocumulus in the upper right.

Fragments of cumulus scattered across the photo with a small patch of stratus or altostratus just up and left of center.

Definite cumulus with stratus or altostratus upper right.

Stratus

Here is our morning weather map at 1600Z (11:00 a.m. CDT). Low overcast covers the Great Lakes and Ohio Valley west to eastern South Dakota,. Nebraska, and eastern Kansas. The low center is centered over northern Kentucky. The cloud photos above are taken from Cedar Falls, Iowa (northeast Iowa) where cloud ceilings have been less than 1,000 feet.

Practice your weather map reading skills by decoding the weather observations. To learn how use our website instructions found by clicking this link: https://www.weatherbriefing.com/observing-forms

Surface Map, Tuesday, May 19, 2020, 1600Z, Map Plotted using Digital Atmosphere, available at www.weathergraphics.com.

Here is the GOES-16 visible satellite image at 11:31 CDT this morning. A large low pressure system centered over Kentucky is meandering slowly over the Ohio Valley and spilling clouds as far west as Nebraska. The clouds shown in the photos above are part of this storm system.

GOES 16 image, USA Visible Satellite Image, 1631Z (11:31 CDT) showing Low centered over Northern Kentucky with cloud shield covering eastern and central USA. Image Courtesy of NOAA.

Clouds of the Day - Monday, May 18, 2020

Stratus with the Sun low in the west.

Stratus with overcast sky.

Clouds of the Day - Sunday, May 17, 2020

Today was a change from the past several days. Just scroll down to see the difference in cloud types compared with today. Today featured stratus, one of ten principal cloud types. Stratus is a gray cloud layer with a nearly uniform base and is in the low cloud family. Stratus is not a precipitation type cloud except it will occasionally produce drizzle when the relative humidity is very high from the cloud base to the surface. It can be found in patches or a sky covering sheet. Stratus can obscure the Sun or sometimes the disk of the Sun is visible.

Here are four pictures of stratus as it appeared today.

Stratus with drizzle

Stratus with drizzle

Evening stratus are no different that mid-day stratus but the Sun low in the west created this dramatic scene. It looked a little ominous but these stratus were harmless, like all other stratus. The lightning made the difference.

Stratus in the evening. The sky was overcast giving a look that was completely different that the picture to the left.

Clouds of the Day - Saturday, May 16, 2020

Cirrostratus

Cirrostratus low on the north horizon

Cirrostratus covering nearly th entire sky. Contrail splitting the photo in two.

Cirrostratus covering the entire sky with halo arouind the Sun.

Altocumulus lenticularis dissipating.

Several lens/saucer shaped clouds - Altocumulus lenticularis. The best examples of lenticularis

Cumulus clouds under Cirrostratus.

More cumulus under cirrostratus.

Sky full of cumulus.

More cumulus in various stages of development covering the sky.

Clouds of the Day - Friday, May 15, 2020

Cirrostratus (Looking South)

Cirrostratus (Looking South)

Cirrus and Cirrostratus (Looking South)

Cirrus looking north

Cirrus fibratus (cirrus with fibers) looking north

Altostratus in waves

Cirrus (top half) , cirrostratus (bottom)

Clouds of the Day - Thursday, May 14, 2020

Stratus (drizzling at time of photo)

Stratus

Stratus with fog visible

Altocumulus (center and left) altostratus with altocumulus in background

Altocumulus in cells (upper left) and waves/Altostratus (Lower right half), Fall streaks (lower left to upper right)

Altocumulus (top, left), fall streaks of ice crystals (center and right)

Altocumulus

altostratus (lower left), cumulus (lower center to right), thin altostratus upper half)

Clouds of the Day - Wednesday, May 13, 2020

Cirrostratus

Cirrostratus

Cirrusstratus (top) and altostratus (bottom)

Altostratus and Altocumulus

Mostly altocumulus with patchy altocstratus

Altostratus with altocumulus (top right)

Altostratus with altocumulus (bottom and uper center)

Alto stratus and Altocumulus

Altostratus with altocumulus (center and upper left of center)

Clouds of the Day - Tuesday, May 12, 2020

Altocumulus is one of ten principal cloud types. It occurs in the mid-levels of the atmosphere between the altitudes of 6,500 to 20,000 feet. Altocumulus occurs in a layer or patches of wavy, round, rolling, laminated shapes. The individual cloud elements when viewed more than 30 degrees above the horizon subtend an angle of 1 to 5 degrees. They appear smaller than cumulus that form in the low levels. They are made of small liquid cloud droplets or ice crystals. Even when temperatures are below freezing liquid droplets often occur in these clouds. This is known as supercooled water.

Today the sky has various types of altocumulus on display. Many of the different types are represented in the photos below. You will see individual cloud cells, wavy clouds and combinations of both shapes. In the first five photos the clouds look soft and fluffy. After that the sky changed. It transitioned from cellular to wavy altocumulus and finally cirrus.

Altocumulus (cells and wavy)

Altocumulus (cells and wavy)

Altocumulus (cells and wavy)

Altocumulus (cells and wavy)

Altocumulus (cells and waves)

Altocumulus (waves and small cells)

Altocumulus (waves and small cells)

Altocumulus (cellular)

During the afternoon the sky changed character - from altocumulus to cirrus. Cirrus are high flying clouds above 18,000 feet. Made of ice crystals, cirrus paint spectacular formations over blue sky. An official definition describes cirrus as a ringlet or curling locks of air. The cirrus in the photos play that part well. The bottom photo is strange. This thin line of cirrus may be man made, possibly due to an aircraft. The line of cirrus was in the sky for over an hour and moved from the western sky to the eastern horizon.

Cirrus

Cirrus

Cirrus (man made?)

Clouds of the Day - Monday, May 11, 2020

altocumulus (Cells are subtle)

Altocumulus (cellular)

Cumulus

Cumulus

Cumulus

Cumulus

Clouds of the Day- May 10, 2020

Map Plotted by Digital Atmosphere software available from http://www.weathergraphics.com/

GOES 16 Satellite Image courtesy of NOAA. - 1416Z 5-10-2020.

It’s a chilly Mother’s Day as cold air continues to spread south in to the central and northeastern United States. Here is today’s Clouds of the Day in Cedar Falls, Iowa. The cloud formations today are common during unseasonably cool outbreaks. The May sunshine To learn how to decode surface station model plots on the map above click HERE and scroll down.

Cumulus (lower left and bottom), stratocumulus (lower left corner), Altocumulus (center to upper right)

Cumulus and stratocumulus, Thin altocumulus (upper right)

Cumulus and stratocumulus

Stratocumulus (upper), altocumulus lenticularis (lens shaped)

stratocumulus and cumulus

Base of Cumulus congestus that produced snow pellet shower at a surface temperature of 48 degrees.

More clouds and snow pellet showers approaching from the northwest. Rain and melted snow pellets equaled .03 inches.

Clouds of the Day - May 9, 2020

Altocumulus lenticularis form from waves in the air. Since they form in a stable layer the clouds do not have extensive vertical height. The often have a lens shape or have the profile of an ariplane wing. Look closely at these clouds and you will see the lens/airplane wing shape in these clouds.

Above the altocumulus were cirrus. You will see the cirrus in the background of the altocumulus in today’s photos.

Cirrus and altocumulus lenticularairs

Cirrus and Altocumulus lenticularis

Cumulus

Cumulus and altocumulus

The clouds roll in frm the northwest. Cumulus and altocumulus

Altocumulus and cumulus

Frosty Night Ahead

Chilly high pressure is centered over Nebraska at mid-afternoon. The air is very dry with relative humidity around 30% or lower. Strong northerly winds and sinking motion ahead of the high pressure center are ushering very dry air across the Midwest.

If you would like to know how to decode the surface station model plots on the map go HERE on our website. Decoding the surface observations on the surface map below reveals current temperatures in the upper 40s and 50s in Minnesota, Iowa, Nebraska, and Wisconsin. Dew points are in the teens and low 20s. That with clear skies and diminishing winds will set the stage for frost and freezing temperatures east of the high pressure ridge from the Plains east to the Great Lakes, Ohio Valley and Mid-Atlantic States. See your local forecast at www.weather.gov.

Clouds of the Day - May 8, 2020

Clear skies ahead of a large high pressure area have produced beautiful blue skies today. The air is very dry which will lead to frost and freezing temperatures tonight. Our median last frost date here is May 4th. The blue sky is striking today. The blue is caused by the scattering of sunlight by our atmosphere. The solar spectrum contains all light colors we see. Because our atmosphere scatters more blue and violet light than other colors the sky looks blue. Without our atmosphere our sky would be black. To prove it just look at the second photo below.

Clear blue sky this morning

Here is a photo taken from the Moon during the Apollo 11 mission, probably by astronaut Buzz Aldren. The photo shows black sky with Earth in the background during the lunar day. Because the Moon has no atmosphere sunlight is not scattered and the sky appears black - unlike Earth which has blue sky because of the scattering of sunlight. By the way, on average a lunar day lasts approximately 29.5 Earth days.

Apollo 11 photo probably taken by Buzz Aldren from the surface of the moon. Photo courtesy of NASA and found HERE

A few low clouds developed during the late morning and afternoon. The clouds were the result of weak updrafts during the heat of the day. Because the clouds were borderline puffy they are considered to be cumulus. Since they were weak with little vertical development we call them cumulus humilus - a humble cumulus.

All clouds fit into a High, Middle, or Low cloud family - based on their altitude. Cumulus are in the Low Family. The name is abbreviated Cu. Cumulus is one of ten principal cloud types. It forms as detached cloud elements which are usually dense with sharp distinct outlines. Cumulus have a vertical structure with rising heaps, towers or domes. Where the Sun shines on the cloud it is usually a bright white color. Its base and areas in shadow are dark.

See our cloud atlas for more information.

Cummulus

Cumulus

Today’s solar radiation chart (May 8th) shows where clouds temporarily blocked the Sun. The greatest decrease in radiation occurred as a dense cloud passed over the Sun. Other less dense clouds made only small changes in the amount of radiation reaching the sensor. When using sunlight for the generation of electricity it is clear that large changes in voltage can occur over very short time periods. The trace from late morning on the 7th shows that cloud cover was not only variable over the short term but in general the amount of generation would be much lower throughout the day compared to today.

Clouds of the Day - May 7, 2020

Today dawned with thin altostratus/altocumulus overhead but quickly turned mostly cloudy and stratocumulus filled the sky.

Altocumulus. Very thin altocumulus allowing much of the blue sky to show through the cloud.

Stratocumulus taken from an angle greater than 45 degrees.

Stratocumulus. Photo taken at an angle less that 45 degrees.

Stratocumulus. Photo taken from almost directly below the cloud base. THis view and the overall structure is rather unusual. NOtice how the clouds were arranged in row.

Stratocumulus. Again this is somewhat unusual because the cloud elements were larger than usual for this type but the vertical extent was limited.

Altostratus

Altostratus. This cloud was definitely a layered flat cloud type making it a stratus formation. The disk of the Sun was dimly visible and there is a hint of a rolling structure indicated by the darker bands.

Altostratus and Cumulus. The altostratus in in the background and there may even be cirrus up in the right upper corner. The lower clouds are cumulus.

This is another photo of mixed cloud types. The darker base is associated with a cumulus congestus cloud. There are smaller elements of cumulus and altocumulus.

This is another view of the photo to the left but this view is moved more to the west. The same cloud types of cumulus, altocumulus and altocumulus are all in this photo.

Altostratus in the background with the base of cumulus congestus and cumulus and cumulus fractus in the foreground. Cumulus conguestus is a larger version of cumulus after the cumulus humilus and cumulus mediocris (medium or mediocre size) and cumulus humilus (humble) stages. Cumulus fractus is a fractured or torn cumulus cloud which comes from fragments of a cumulus type cloud. It is a low cloud.

Clouds of the Day - May 6, 2020

From cirrostratus to cumulus - from sunshine to overcast

Photo is courtesy of NOAA.

The upper left photo below shows cirrostratus clouds which are visible in the GOES 16 satellite image above. The cirrostratus is located over east central Iowa. They appear as wispy clouds with north-south banding and do not obscure the ground below. Cumulus clouds cover most of the remainder of Iowa. As you see below cumulus developed over the Cedar Falls/Waterloo area of northeast Iowa during the day. The photos are placed in chronological order.

The day started with cirrostratus, one of ten principal cloud types. Cirrostratus often appear as a thin veil, whitish in color, with fibrous lines or a smooth texture. Both texture types are represented in the photos below. Cirrostratus are famous for producing haloes around the Sun or Moon. Ice crystals settling in the clouds bend (refract) sunlight to create the haloes. These clouds are found above 18,000 feet where temperatures are below freezing. Cirrostratus can be found in patches but if they spread over the entire sky and gradually thicken be on the look out for an approaching storm system. They spread out in advance of significant low pressure systems and were a warning to weather wise inhabitants of the plains. If the veil of cirrostratus becomes opaque, blocking the disk of the Sun from being visible, the cloud has transitioned to thicker and lower altostratus.

Cirrostratus

Small cumulus in foreground with Cirrostratus in background

Before noon another principal cloud type began to form - cumulus (top right). The first stage of cumulus is cumulus humilus which is a small humble cloud. If cumulus remain as humilus they are nicknamed fair weather cumulus. Today the cumulus continued to grow into cumulus mediocris (a mediocre or medium size puffy cloud) and then on to cumulus congestus (larger and congested looking). Congestus is the last stage before precipitation begins to fall from the cloud. The next stage would be cumulonimbus, a large cumulus cloud producing rain or virga (rain not reaching the ground).

Cumulus mediocris (mediocre, Medium) with cirrostratus in background

Cumulus Mediocris in foreground with Cirrus and cirrostratus in background

Looking at the bases of cumulus clouds

Cumulus humilus (humble/small)

Suddenly, the sky turned threatening. Instead of blue sky punctuated by cumulus, the cumulus swelled into cumulus congestus. Then, just as suddenly, the cumulus flattened as updrafts lost their upward impetus. The clouds spread out and flattened, blotting out the Sun. The flattening of the cumulus occurred toward evening. By late afternoon the Sun begins losing its ability to heat the earth. As temperatures cool updrafts weaken. The cumulus flatten and spread over the sky further blocking the Sun. Any threat of showers comes to an end.

Cumulus, Cumulus congestus, Altocumulus

Altocumulus, altostratus

The solar radiation profile for today is on the far right of the chart below. Notice how the trace increases as the Sun climbs in the sky. It reaches its highest point at local Noon - today at 1:31 p.m. CDT. By the way, local Noon will occur later each day until the summer solstice occurs in June.

Compare the cloud photos today with the solar profile. Instead of a smooth increase in radiation there were small increases and decreases due to cloud cover. 1:31 p.m. would be the time of the peak radiation - except for the cloud cover. Notice the first large drop in radiation and its sudden recovery. That was followed by another large drop that was permanent. That’s when the Sun became completely covered for the remainder of the day. Clouds filled the sky, dropping the radiation from 1,000 watts per square meter to less than 500 watts and then 250 watts. Compare the chart with the photos to see how the cloud cover changed and how it affected the solar radiation reaching the ground.

Clouds of the Day - May 5, 2020

It’s been raining steadily this morning. So far, between 1:30 a.m. and 11:00 a.m. the rain gauge has measured .36 inches of rain which is a rainfall rate of .04 inches per hour. Check the rain gauge meteograph below.

The cloud type this morning is nimbostratus. Nimbostratus is one of ten principal cloud types. It is gray, or sometimes darker, because of its thickness and falling precipitation. It is classified as a middle cloud because it forms in the mid-levels, usually as altostratus, and thickens and lowers. Falling rain (or snow) gradually saturates the lower levels, lowering the cloud base into the lower levels. Nimbostratus looks the same as stratus but stratus does not have precipitation, except possibly drizzle.

Note: Look at yesterday’s blog. The day started with sunshine but altostratus spread overhead during the day. The altostratus was running ahead of today’s storm system and was the forerunner of today’s nimbostratus and rain.

Nimbostratus

Nimbostratus

Meteograph of rainfall. This chart ends at 11:40 a.m. with .41 inches of rain. Light rain continues.

Compare today’s (5th) solar profile with yesterday’s (4th) and the day before (3rd). Look at the cloud photos for each day below. The photos each day are displayed in chronological order. The 3rd recorded sudden large variations in solar energy due to rapidly changing cloud cover. The 4th began sunny but quickly clouded over with altostratus. Variations in the cloud thickness are plainly visible in the profile. Today began with light rain and thick nimbostratus which is evident on the very low amount of solar energy getting to the ground.

The radar image below shows where rain is falling over central Iowa, including the Waterloo and Cedar Falls area, as of 11:55 this morning. The entire area is shifting eastward and time-lapse shows slow rotation centered in the rain area southeast of Storm Lake in northwest Iowa. The rain is light but steady where it is falling. The radar image is from Radarscope software available here: https://www.radarscope.app/.

The rain gauge data below was added this May 5th post on May 6th. It shows the complete rainfall traces for total rainfall (blue) and rainfall rate per hour (magenta). The first measurable rain (blue line) was at 1:30 a.m. on May 5th with the last measured rain at 9:20 p.m. The rainfall rate (magenta) is indicated across the bottom of the graph with most reports at .06” per hour up to .12” per hour. The sudden drop in the accumulated rainfall is at Midnight when the gauge starts a new day at zero.

Clouds of the Day - April 4, 2020

Cirrus and Altocumulus

Cirrus and Altostratus

Altostratus

Altostratus

Altostratus

Clouds of the Day - May 3, 2020

Waves in the air.

When we looks at clouds we often wave patterns. Many, but not all, of the photos below are of clouds that look like waves. They are called gravity waves. Look at each photo carefully and see if you can spot the waves. Some of the photos have waves superimposed on on other waves. Don’t forget to look closely! An eye for detail will be rewarded by seeing multiple waves of different sizes in the same photo.

Gravity waves are set up by air motions of different speed and direction embedded within adjacent layers. They layers ripple much like waves in the ocean. Clouds make the waves visible. Gravity waves are also caused by up, down, and horizontal motions in and around thunderstorms or air crossing mountain ranges. The air oscillates up and down and side to side. If moisture is sufficient clouds form where air is rising with clearing where the air descends. Look at the photos below and see if you are able to find waves. Hint: Not all of the photos have waves.

This chaotic looking sky includes several cloud types. The primary types are altocumulus which are front and center, cirrus which are visible at a higher altitude and plainly visible in the upper right of the photo, altocumulus upper left, and altocumulus and probably altostratus lower left.

This photo has multiple types of altocumulus spread over the entire frame.

Here we have several types of altocumulus again. The altocumulus in the upper left have a very distinct puffy cumulus structure while other stratocumulus in the lower center have a more layered look so there is both a stratus and cumulus structure with waves and cells that put them in the altocumulus category.

This is the same part of the sky but with the photo moved more to the left. The couds are almost entire altocumulus of different varieties but look closely and you will see a thin cirrostratus layer visible behind the altocumulus on the right and lower part of the photo. This is cirrostratus.

Look closely at this photo for many clouds of different sizes and shapes. There are both altocumulus and altostratus. The altocumulus are wave type clouds although there are some very small individual cells visible in the lower left and also i the upper left quarter. The altostratus are visible as smooth layer type clouds. THere are waves in varying sizes across the entire photo.

If these clouds make you think of waves on a lake or the ocean - they should! The atmosphere is undulating in a stable layer so the clouds don’t grow with height. THere is a wide separationg in the waves. Look at other clouds in today’s photos and you will see many waves of different sizes. Did you notice the condensation trail (contrail) in this photo? It is from an aircraft flying much higher than these clouds.

MOre wave type altocumulus. THere is also an altostratus layer on the right that is “imipressed” with waves.

THis photo is rich with complex cloud structures. These structures reveal a varitey of atmopsheric motions this morning. There are altocumulus all over this photo. Notice the larger waves across the top, small cells in the upper right, a combination of cells and waves across the bottom. THere are altostratus across the middle with embedded cumulus cells and scattered wave structures.

Altocumulus

Altocumulus

Altocumulus with a mix of altocumulus and altostratus lower left. Notice the faint streak of white covering part of the lower left altocumulus near the trees. It is falling ice crystals trailing from the dense altocumulus in the upper left of center.

Cellular and wave form altocumulus

Altocumulus and altostratus

Altocumulus and altostratus

Wave form altocumulus with altostratus that have faint wavies.

Cirrus

Altocumulus and altostratus

Cirrus and cirrostratus with patches of altocumulus/altostratus

Cirrus upper right with dense sirrus center and alto stratus lower left

Cumulus

The photos were taken in chronological order between 10:00 a.m. and 5:00 p.m.