The an initial figure above (see p.101 in the photocopied course Notes) reflects a water droplet in equilibrium v its surroundings. The droplet is evaporating (the 3 blue arrows in the figure). The rate of evaporation will rely on the temperature that the water droplet. There will be some evaporation also from a droplet the is very cold. The droplet is surrounded by air the is saturated with water vapor (the droplet is inside a cloud whereby the loved one humidity is 100%). This method there is sufficient water vapor to be able to supply 3 arrows of condensation. Due to the fact that the droplet loses and also gains water vapor at equal rates it doesn"t thrive or shrink. What is required to save an ice decision happy?

We"ll i think that everything is in ~ the exact same temperature. An ice crystal won"t evaporate as promptly as a water droplet (only 1 arrowhead is shown, it might have been 2 simply as lengthy as its no 3). Walk from ice cream to water vapor is a enlarge "jump" 보다 going from water come water vapor. Over there won"t be as many ice molecules with enough power to make the jump. A kind of analogous case is displayed in the figure below. The course instructor could and also most the the world in the room could jump indigenous the floor come the height of a 10 or 12 inch tall box. It would certainly be much tougher to jump to the peak of the table (maybe 30 inches turn off the ground) or the cabinet (maybe 36 inches) at the prior of the room. Over there wouldn"t be together many world able to carry out that. To be in equilibrium the ice crystal only requirements 1 arrow of condensation. There doesn"t should be as lot water vapor in the air neighboring the ice crystal to supply this lower rate that condensation.

now what wake up in the combined phase region of a cold cloud is the ice crystals find themselves in the very moist surroundings necessary for water droplet equilibrium. This is displayed below.

The water droplet is in equilibrium (3 arrows of evaporation and 3 arrows of condensation) through the surroundings. The ice decision is evaporating more slowly than the water droplet. Due to the fact that the ice decision is in the same surroundings as the water droplet water vapor will be condensing onto the ice crystal at the same rate as onto the water droplet. The ice crystal isn"t in equilibrium, condensation (3 arrows) exceeds evaporation (1 arrow) and also the ice cream crystal will grow. That"s what provides the ice cream crystal process work.
The equal prices of condensation are presented in the figure listed below using the previously analogy.

most everyone can manage to do the huge or the small jump down.
Now us will check out what can take place once the ice decision has had actually a opportunity to prosper a small bit.

Once an ice crystal has grown it i do not care a snow crystal (this number is on p. 102 in the ClassNotes). Snow crystals have the right to have a variety of forms (plates, dendrites, columns, needles, etc.; this are dubbed crystal habits) relying on the conditions (temperature and moisture) in the cloud. Dendrites are the most common because they kind where there is the most moisture easily accessible for growth. With more raw material obtainable it makes sense there would certainly be more of this particular snow decision shape.

You are watching: Hail can fall from both cumulonimbus and nimbostratus clouds.


Here are some actual photographs of snow crystals (taken through a microscope). Snow crystals space usually 100 or a few 100s that micrometers in diameter (tenths of a millimeter in diameter). The different shapes are called "habits".
You"ll discover some much far better photographs and a heap of additional information around snow crystals at www.snowcrystals.com.


A variety of points can occur once a snow crystal forms. An initial it can break into pieces, then each the the pieces can flourish into a brand-new snow crystal. Since snow crystals room otherwise in rather quick supply, ice crystal multiplication is a means of enhancing the quantity of precipitation that at some point falls indigenous the cloud.


Several snow crystals deserve to collide and stick with each other to kind a snowflake. Snow crystals are small, a few tenths the a millimeter across. Snowflakes can be much larger and are consisted of of many snow crystals stuck together. The sticking with each other or clumping with each other of snow crystals is dubbed aggregation (I typically forget the name of this procedure and don"t intend you come remember it either).

The next procedure and bit are something that i hope you will remember.

Snow crystals deserve to collide through supercooled water droplets. The water droplets might stick and also freeze to the eye crystal. This procedure is dubbed riming or accretion (note this isn"t referred to as collision coalescence even though that is the very same idea). If a snow crystal collides with enough water droplets it deserve to be totally covered through ice. The resulting fragment is referred to as graupel. Graupel is occasionally mistaken because that hail and also is called soft hail or eye pellets. Rime ice has actually a frosty milky white appearance. A graupel fragment resembles a miniature eye ball. Graupel particles regularly serve together the nucleus because that a hailstone.

Graupel is make of milky white frosty rime ice. Sleet, we will certainly find, is made of clean ice. Below are some images to aid you better appreciate the distinctions in appearance.


Here"s a snowball. It"s white and you can"t see through it. It"s comprised of many smaller crystals the ice. Graupel is just a little snowball. Resource
The ice cream in a eye cone is usually the same. Several smaller chunks of ice. The ice cream is frosty white (before you included the flavored syrup. ) resource
clear transparent crystals that sugar source of this picture
street cubes are consisted of of many much smaller grains the sugar and have a frostly white appearance.
Graupel is often mistaken for hail. This figure gives friend an idea of exactly how hail forms.


In the figure above a hailstone starts through a graupel particle (Pt. 1, colored environment-friendly to represent rime ice). The graupel falls or gets lugged into a part of the cloud whereby it collides through a big number the supercooled water droplets i beg your pardon stick come the graupel yet don"t instantly freeze. The graupel it s okay coated through a layer of water (blue) at Pt. 2. The particle then moves right into a colder part of the cloud and also the water great freeze creating a great of clear ice cream (the clean ice, colored violet, has actually a distinctly different appearance native the milky white rime ice), Pt. 3. In Tucson this is often the only example of hail that you will certainly see: a graupel particle core through a solitary layer of clean ice.
In the significant thunderstorms in the central Plains, the hailstone have the right to pick up added layers of rime ice and clear ice and also hailstones deserve to be created of many alternate layers that rime and clear ice. One unusually big hailstone (around 3 inches in diameter) has actually been cut in fifty percent to show (below) the various layers that ice. The photo below is close to actual size. If something favor this were to hit you in the head it would split your skull open. Here"s part pretty an excellent video the a hailstorm in Phoenix.


Hail is developed in solid thunderstorms with tilted updrafts. You would never ever see hail (or graupel) falling indigenous a nimbostratus cloud. A new record to be apparently set for a huge hailstone in Hawaii in march of this year. Hawaii is an unusual place for hail this large to be found.

Hail is developed by thunderstorms (cumulonimbus clouds) due to the fact that the cloud is thick and thunderstorms have strong updrafts that deserve to keep the hailstone in the cloud where it can grow. Hail would certainly never fall from a nimbostratus cloud they room too thin and the updrafts room too weak. The figure below wasn"t presented in class.

See more: Cubic Meters Per Minute To Cfm To Cubic Meter/Minute, Cubic Meters Per Minute To Cubic Feet Per Minute


This thunderstorm has a tilted updraft. The farming hailstone have the right to fall back into the updraft (rather than falling the end of the cloud) and be carried earlier up toward the top of the cloud. In this means the hailstone can finish several cycles v the inner of the cloud.

Finally ~ above p. 103 in the ClassNotes are illustrations of several of the things that can take place once a precipitation particle falls from a cloud. I"ve break-up this right into two groups for clarity.
Essentially every the rain that falls in Tucson is created by the ice decision process. The left figure above shows how this happens. A fallout’s graupel bit or a snow flake moves right into warmer air and also melts. The resulting drops that water fall the remainder of the method to the ground and also would be referred to as RAIN. In the middle snapshot graupel particles have the right to survive the expedition to the ground there is no melting also in the summer. Many world on the floor would speak to this hail but that wouldn"t be rather right. Graupel is less typical in the winter since it originates from thunderstorms and also they don"t form very frequently in the winter. Snow have the right to survive the pilgrimage to the ground in the winter but not the summer. occasionally the fallout’s raindrops will certainly evaporate before reaching the ground. This is called VIRGA and is pretty common early in the summer thunderstorm season in mmsanotherstage2019.com as soon as the waiting is still pretty dry. Lightning that comes from thunderstorms that aren"t creating much precipitation is called "dry lightning" and also often beginning brush fires.
Rain will periodically freeze before reaching the ground. The resulting fragment of clear ice cream is referred to as SLEET (it has a really different appearance indigenous graupel). Freezing RAIN by contrast only freezes once it will the ground. Whatever on the ground (the photo shows a car) can acquire coated v a thick layer of ice. it is virtually impossible to drive throughout one of this "ice storms." periodically the coating of ice is heavy sufficient that branches ~ above trees are broken and also power lines are carried down. It sometimes takes number of days for power to it is in restored. Last, prior to we leaving the object of clouds and precipitation, part information around satellite photographs of clouds.
we only had actually time for the product on IR satellite photographs yet I"ve included information on visible photographs likewise (visible satellite photographs of clouds won"t be extended on the quiz). The figure listed below wasn"t displayed in class.

when you watch satellite photographs of clouds top top the TV weather friend are most likely seeing an infrared satellite photograph. 1. An infrared satellite photograph detects the 10 μm IR radiation actually emitted by the ground, the ocean and also by clouds. Friend don"t depend on see reflected sunlight, for this reason clouds have the right to be photographed throughout the day and also at night, 24 hrs per day. You may recall that 10 μm radiation is in the center of the mmsanotherstage2019.comspheric window, therefore this radiation is able come pass with air without being absorbed. If clouds don"t gain in the way, you deserve to see the ground and the ocean on an IR photograph. 2. Clouds carry out absorb 10 μm radiation and also then reemit 10 μm IR radiation upwards towards the satellite and down towards the ground. That is the radiation emitted through the peak surface the the cloud that will travel v the mmsanotherstage2019.comsphere and up come the satellite. The peak surface that a low altitude cloud will certainly be relatively warm. Warmer objects emit more powerful IR radiation 보다 a cool thing (the Stefan Boltzmann law). This is presented as grey on an IR satellite photograph. A grey unimpressive looking cloud on an IR satellite photograph might actually it is in a thick nimbostratus cloud the is developing rain or snow. 3. Cloud tops uncovered at high altitude room cold and emit IR radiation in ~ a lower rate or reduced intensity. This shows up white on one IR photograph. 4. Two really different clouds (a thunderstorm and a cirrostratus cloud) would certainly both show up white top top the satellite photograph and also would be daunting to distinguish. Meteorologists are interested in locating thunderstorms because they can develop hazardous major weather. This can"t be done using simply IR photographs. 5. And here is what ns think is one of the most amazing things you deserve to see on one IR satellite photograph, that doesn"t have actually anything to carry out with clouds. The ground alters temperature throughout the food of the day. On one infrared satellite computer animation you can watch the ground readjust from dark grey or black color (afternoon when the floor is warmest) come lighter grey (early morning once the floor is cold) during the course of a day. Since of water"s high particular heat, the ocean right together doesn"t readjust temperature much throughout the day and also remains the same shade of grey throughout the day.
Here"s a attach to an IR satellite photo loop ~ above the UA mmsanotherstage2019.comspheric sciences Dept. Webpage. Clock the ground readjust from irradiate grey to dark grey. By comparison the ocean"s shade of grey doesn"t show up to change at all. 24 hours of IR satellite photography (National Weather Service) The remaining material wasn"t spanned in class
visible satellite photographs
1. A visible satellite picture photographs sunlight that is reflect by clouds. It shows what friend would check out if you were the end in space looking under at the earth. You won"t check out clouds top top a clearly shows satellite photo at night. 2. Special clouds are good reflectors and appear white. The low altitude class cloud and also the thunderstorm would both show up white top top this photograph and also would be an overwhelming to distinguish. 3. Diluent clouds don"t reflect as much light and also appear grey. Here"s a review
The figure listed below shows just how if you integrate both visible and also IR photographs girlfriend can begin to distinguish between different species of clouds.
You have the right to use this figure to answer the satellite picture question that is on the Quiz #3 research Guide.