To purchase our 24” x 36” full color cloud chart, go to our online store. It is suitable for framing in a standard 24” x 36” frame.
Learn how to identify clouds by following the Clouds of the Day posts below.
My least favorite clouds are featureless Stratus with diffuse cloud bases. Low level moisture in a northwesterly flow of air that is moving in behind low pressure centered near the Great Lakes is gently rising in the stable air. The result is a low cloud deck several hundred feet above the ground. True Stratus might produce a little drizzle but that is about it. Otherwise the most we can hope for will be clearing skies and bright sunshine before the day is over.
Before the time of satellite imagery and computer weather forecast models an observer looking at this sunset could only guess if there was a storm over the horizon.
This photo looks to the southwest toward Cirrus, Altostratus and Altocumulus clouds. As luck would have it these clouds were detached from the real storm that would approach from the northwest in 48 hours. These clouds were associated with ‘warmer’ air aloft moving our way from the Southern Plains. The air was being lifted enough to condense its water vapor into tiny water droplets and ice crystals.
The sky does provide hints of what is to come if you know what to look for. The more you know about what is happening the more hints clouds can provide. Having a barometer to watch air pressure rise, fall, or remain steady is helpful. If pressure is changing quickly a change is more imminent. Noting the wind direction and speed and how they are changing helps forecast what is on the way. Your forecasts won’t be perfect but learning about the wind, air pressure, and clouds opens the door to being more weather wise!
In this case we ended up with 4 inches of snow.
A lone bird is caught in flight headed west on a cold December morning. Northwest winds were scouring out morning fog and the remnants of the fog was now on the verge of forming Cumulus clouds. Just a couple of of hours earlier dense fog shrouded the landscape. In aviation terminology pilots had to follow Instrument Flight Rules (IFR). As the fog dissipated conditions improved to VFR (Visual Flight Rules). We don’t see many birds flying during episodes of dense fog. On this morning temperatures were in the teens as drier air mixed out the moist air and dissipated the fog and birds once again took to the air.
This hand held photo of the constellation Orion was taken about an hour after the Moon ended its occultation of the planet Mars on the evening of December 7th (2022). Orion’s nearly vertical belt is plainly visible just right of center between the Altocumulus wave type clouds. A thin streak of light is visible just to the right of the wave cloud farthest to the lower left. It is likely from an aircraft flying toward the east.
These altocumulus have formed in a mid-level layer of moist air where wavy air motion reaches a peak. The flow is right to left. The clear sky between the clouds occurs where the waves are sinking. The alternation rising and sinking air creates a series of clouds and clear strips.
Photo copyright 2022 by Craig Johnson, Weather Briefing, LC
Altocumulus lacunosus
Cirrus, cirrocumulus, altostratus, altocumulus
Altocumulus lacunosus, altostratus, altocumulus
All of the photos from today were taken at the same time from the same location. The camera was just pointed in different directions. Viewing the sky can be a pleasant past time and may generate many questions about why and clouds form and what causes the different shapes.
The photos from today reveal classic Cirrostratus clouds. Cirrostratus indicate the saturation of a broad layer of the atmosphere. The cloud layer is very thin and the ice crystals only dim the sunlight. This photo and the one about it were taken about a minute apart. Notice the difference in the position of the jet CONTRAIL between the photos.
Cirrostratus with a CONTRAIL
Cirrus fibratus and cirrostratus
The photo above features long thin strands of ice crystals blown by strong steady high winds aloft. The clouds were stretched across a wide area of the sky with an even texture because of the steady winds. As with all Cirrostratus, these clouds dimmed the sunlight but did not block it.
Cirrus, cirrostratus, cirrus fibratus, a CONTRAIL (Condensation Trail)
Here is more Cirrostratus in the form of sheets and filaments. The CONTRAIL is long and distinct indicated the layer were it is flying is moist, which slows the sublimation of the ice crystals. Sublimation occurs when ice changes directly to water vapor without first melting into a liquid. Water changes from water droplets to a vapor by evaporation.
One more look at the Cirrus sheet shows Cirrostratus and Cirrus fibratus.
Cirrus fibratus (thin fibers in bands) and Cirrus uncinus (hooked cirrus) covered the southern sky early this afternoon. This photo is looking south from Cedar Falls, Iowa.
One explanation for the formation of Cirrus uncinus indicates that a region of rising air forms the ‘head’ of the cloud while the tail forms when ice crystals precipitation out of the head and fall into slower moving air below the head. The heads appear to be at the highest point and leading end of the cloud where the formation is dense with falling ice crystals. As the crystals fall they trail behind the head because the air below is moving slower.
The leading edge of the cirrus looked like long thin fibers.
Sunrise with stratocumulus and snow flurries. The same air mass that was bringing heavy snow squalls to the lee shores of the Great Lakes brought flurries and light snow to portions of the Upper Midwest. Temperatures were in the lower teens at dawn.
These Stratocumulus were producing snow showers with light accumulations. Most Stratocumulus do not precipitate but if they do it us usually drizzle. In a cold atmosphere with low level moisture we can get quick bursts of mainly snow flurries.
Snow showers are occuring with this cumulus cloud. The streamers can be seen hanging below the cloud and looking lower the white ‘hazy’ sky is snow falling in the cold atmosphere with temperatures in the teens.
More falling snow is visible below the white cloud tops in this photo.
A flock of Canadian Geese is headed west toward a wetland on the west side of Cedar Falls. The Sun was rising in the southeast this morning and its light was being filtered by a low deck of Stratus cloud. Low level cold air cut underneath a Pacific Air Mass aloft creating the stable stratus cloud layer. Temperatures were in the upper 20s.
Photo Copyright by Craig Johnson, Weather Briefing, LC, 16 November 2022, Cedar FAlls, Iowa.
Looking southeast toward the sunrise we see a bright diffuse solar disk on the rise. The light is diffused by the shallow cloud layer giving the Sun a frosted glass appearance.
Photo Copyright by Craig Johnson, Weather Briefing, LC, 16 November 2022, Cedar FAlls, Iowa.
There was blue sky too. As colder drier air moved in the Stratus was broken into fragments allowing sunshine and areas of blue sky to appear. Temperatures responded lightly with readings touching 30 degrees during the day.
Photo Copyright by Craig Johnson, Weather Briefing, LC, 16 November 2022, Cedar FAlls, Iowa.
The photos here show snow scenes this morning. So far there is 2 inches of new snow. The sky is covered with Nimbostratus (Ns) and very light snow falling.
Taken at 11:30 this morning these clouds looked cold. Temperatures in the 20s and no leaves on the trees added to the effect. The Sun was visible through the cloud deck, which revealed the cellular cloud pattern of Cumulus clouds.
‘Alto’ means high. This photo shows clouds above 6,000 feet (2,000 meters), which we refer to as the middle layer of the atmosphere. It is just above the lowest layer, which is near the surface. The lowest Cumulus cloud type is named Cumulus. However, because the clouds in this photo are just above the lowest layer, they are named Altocumulus (high cumulus). The higher cloud layer above these clouds is where ‘Cirrus’ clouds are found. Cumulus in that layer are called Cirrocumulus.
Photo copyright by Craig Johnson in Cedar Falls, Iowa on November 8, 2022.
Iridescent clouds are clouds of ice-particles. They display brilliant spots or borders with red and green colors. The colors are seen 30 degrees or less from the Sun. The ice particles are very small and are nearly all of the same size. Irisation, which is the coloration seen at the cloud edges, are mostly red in this photo but there are hints of green tinges too. The clouds displaying the irisation are Altocumulus with a distinct pattern caused by wavy motion in the wind.
Winter is raising its head so here are a few definitions of winter precipitation types. The information is adapted from the Glossary of Meteorology published by the American Meteorological Society in 1959.
Today was a rainy Friday. As of 8:45 p.m. the rain gauge recorded 1.23 inches of rain with light rain still falling. The photo below was taken this afternoon. It shows wet streets and if you look closely you might even see a few splashes of rain drops hitting the concrete.
The ground is wet from continuous rain. Looking skyward we see the dull gray sky of Nimbostratus clouds. Nimbus means rain and a Nimbostratus is a cloud with rain. Rain must be present without thunder or lightning for the cloud to be Nimbostratus. If thunder and lightning are present with rain the cloud is Cumulonimbus.
Nimbostratus usually have an indistinct cloud base below 6,000 feet which is obscured by rain. Nimbostratus may form in the middle levels as altostratus and then lower and evolve into Nimbostratus as rain begins to fall and moistens the lower level of the atmosphere. The cloud base lowers and gradually becomes obscured.
Finally let’s look at two charts. The first chart shows the thermograph of the past 48 hours. T his chart is plotting temperature, dew point, and relative humidity from left to right. We can see when the leading edge of the cold front passed just before 4:00 a.m today. Notice how the temperature trace (solid red line) suddenly begins dropping from near 60 degrees to the lower 40s by Noon. The dew point also began dropping with the passage of the front as drier low level air moved in from the west. The relative humidity began to rise (blue dashed line) as the temperature cooled and rain began around 8:00 a.m. The relative humidity increases when the temperature cools and the dew point remains about the same and it also increases when rain evaporates more moisture into the air as water vapor.
Finally, here is the trace from the rain gauge. The blue link shows the total rainfall with time and the purple line shows the rainfall rate with time in inchs/hour. At the end of the trace the total was 1.25 inches.
It has been bone dry over the Plains and much of the western United States. The chart below shows the extent of the dry conditions from the Plains States and across the southern and western United States.
U.S. Seasonal drought outlook is courtesy of NOAA.
The map below shows where precipitation is expected through Friday morning. The storm will spread eastward in to the weekend. Rain is falling on the east side of the storm with snow on the west side into the higher terrain of the Rockies.
Forecast chart is courtesy of NOAA/National Weather Service.
After many days of clear skies things are getting more active here. The following photos show the progression of clouds today. The first photo shows Cirrus in the upper right corner and a mix of Cirrus and Altostratus in the upper left. The lower half has Altocumulus and Altostratus clouds. The photo was taken around 8:30 this morning.
By early afternoon ragged Cumulus appeared as low level moisture appeared.
The dew point trace on the graph below is the green dotted line. Notice how the dew point temperature began to increase around 5:00 this morning and continued to increase in to the afternoon.
Temperature, Dew Point, and Relative Humidity Chart is from the Dyacon Weather Station here at Weather Briefing, LC, Cedar Falls, Iowa
The next photo shows Stratocumulus clouds this afternoon with a layer of Altostratus above with diffuse sunshine coming through the Altostratus. The dark bases of the Stratocumulus are caused by t he clouds being in the shadow of the Altostratus with the cloud bases receiving minimal sunshine. The Stratocumulus are forming as low level moisture from the Gulf of Mexico pushes the dew points into the 50s after being in the 30s for the past several days. The Altostratus are spreading in from the west above 8,000 feet with an increase in mid-level moisture.
After days of clear skies we finally had clouds from the Cirrus family move overhead from the west. CONTRAILS get their name from Condensation Trails - man-made clouds that form from the condensation of water vapor in jet engine exhaust. As long as there is sufficient moisture aloft naturally the addition of more moisture from the engine exhaust raises the relative humidity high enough to condense into a CONTRAIL. Several CONTRAILS are visible in the photo below and over time they either spread into a pattern seen here from the bottom left to the upper right of the photo or they may evaporate where the air is drier as is seen in the CONTRAIL visible in the center of the photo and near the bottom of the screen.
NOTE: Do you see the Moon in the lower left?
Photos by Craig Johnson, Weather Briefing, LC
Photos are by Craig Johnson, Weather Briefing, LC
The photo above is an excellent example of Cirrus fibratus. This is looking northwest in the direction of where the Cirrus were coming. There are also wave clouds in the lower center of the photo which are cirrostratus or high altostratus. Our high temperature reached 76 degrees - a beautiful November day.
Cumulus and Altocumulus
Cirrus uncinus and cirrus floccus
Alsocumulus
Crepuscular Rays
Altocumulus cumulogenitus in center left and low center right
Cumulus and Cumulus congestus
Base of a cumulus congestus with sprinkles of rain; Cumulus lower right
These photos were taken on a recent fine fall day with mild temperatures and light winds. It is deceiving. Overhead above 16,000 feet it is much colder and windier. In fact, at any time of the year it is much colder overhead with temperatures often well below zero. This time of year, it is getting colder here on the ground, and aloft. The transition to winter is underway. These clouds are cirrus with their soft hairlike filaments and protuberances. They are also made of mainly ice crystals. Fallstreaks, also called virga, are trailing the upper clouds as they fall through layers with different wind speeds. It is a “snowstorm” aloft that will someday reach the ground as lower layers cool below freezing.
Our sky can put on quite a show. These show CONTRAILS (Condensation Trails) and clouds. In fact, a CONTRAIL is nothing more than a manmade cloud that formed with the assistance of nature. Jets exhaust a trail of water vapor that condenses in the cold air aloft. If the air is too dry the vapor does not become visible in the form of a cloud. If there is enough moisture in the air (even though the sky may be clear) it will condense forming CONTRAILS. Here we see a mixture of cirrus clouds and CONTRAILS. They change shape with time as they move through different weather regimes overhead such as changes in temperature and wind direction and speed.
CONTRAILs with cirrus fibratus, cirrocumulus, and fallstreaks
Contrails with cirrus fibratus
Cirrus
Copyright 2016-2024, Weather Briefing, L.C.
Cedar Falls, IA 50613, Phone: 319-215-2634, Email: craig@weatherbriefing.com
