WIND - SCAVENGER HUNT

WIND SCAVENGER HUNT

• Use the websites to answer the following questions.
• DUE:  Thursday, April 24

WIND MOVEMENT  http://www.kidsgeo.com/geography-for-kids/0087-wind-movement.php

·        3 important factors affect the direction that wind blows? THE CORIOLIS EFFECT http://www.kidsgeo.com/geography-for-kids/0089-coriolis-effect.php ·        What is the coriolis effect? WIND FRICTION http://www.kidsgeo.com/geography-for-kids/0090-wind-friction-effect.php ·        What things interfere with wind, changing its direction & speed – give examples ·        Whre is the effect of friction important? WIND SPEED http://www.kidsgeo.com/geography-for-kids/0091-wind-speedt.php ·        Wind speed is primarily affected by? Explain TRADE WINDS  http://www.kidsgeo.com/geography-for-kids/0094-trade-winds.php ·        Which direction do winds in Northern Hemisphere move? ·        Which direction do winds in Southern Hemisphere move? ·        What are easterlies winds? WESTERLIES http://www.kidsgeo.com/geography-for-kids/0095-westerlies.php ·        What are westerlies wind? ·        What is the jet stream? POLAR EASTERLIES  http://education.nationalgeographic.com/education/encyclopedia/wind/?ar_a=1 ·        What are polar easterlies? SEA & LAND BREEZES  http://www.kidsgeo.com/geography-for-kids/0098-sea-land-breezes.php ·        How do sea & land breezes work?  Do day & nite differ? (DRAW) MOUNTAIN & VALLEY BREEZES  http://www.kidsgeo.com/geography-for-kids/0099-mountain-valley-breezes.php What are mountain & valley breezes?   Do day & nite differ?   (DRAW) WIND – HISTORY   http://kids.mtpe.hq.nasa.gov/archive/nino/global.html Answer the following questions: ·        What winds would Columbus have used to travel from Spain to the Caribbean? ·        Which winds would he have needed to return to Europe? ·        Would winds have favored European explorers seeking to travel east around the tip of Africa? ·        Wind is caused by? ·        What scale describes & classifies the different wind speeds is the? ·        Wind direction is measured by a? ·        Wind speed is measured with a ? ·        What are the narrow bands of strong winds called which move around the world between about six and twelve miles high? ·        High & low pressure try to reach? ANSWER QUIZ QUESTIONS  http://goo.gl/0O90Fq DRAW & LABEL – Windward & Leeward winds

WEATHER - WIND

What is wind? 
Wind is air in motion. It is produced by the uneven heating of the earth’s surface by the sun. Since the earth’s surface is made of various land and water formations, it absorbs the sun’s radiation unevenly. Two factors are necessary to specify wind: speed and direction.

What causes the wind to blow? 
As the sun warms the Earth's surface, the atmosphere warms too. Some parts of the Earth receive direct rays from the sun all year and are always warm. Other places receive indirect rays, so the climate is colder. Warm air, which weighs less than cold air, rises. Then cool air moves in and replaces the rising warm air. This movement of air is what makes the wind blow.
Wind Direction

Although wind blows from areas of high pressure to areas of low pressure, it doesn't blow in a straight line.  That's because the earth is rotating.  In the northern hemisphere, the spin of the earth causes winds to curve to the right (to the left in the southern hemisphere). This is called the coriolis effect. So in the northern hemisphere, winds blow clockwise around an area of high pressure and counter-clockwise around low pressure.

How Fast Is It? You can estimate wind speed with the Beaufort Scale.  It was developed in 1805 by a Navy admiral to measure wind at sea.  But we can also use it to measure wind on land.

ESTIMATE WIND BY WATCHING OBJECTS MOVE!

Miles Per Hour   Effects <1  Smoke rises straight up, no motion
1-3        Smoke drifts slowly, tree leaves barely move
4-7        Leaves rustle, wind felt on face

8-12      Leaves and twigs move, dust raised from ground

13-18    Small branches move, dust and paper blown away.

19-24    Small trees and large branches sway

25-31    Big branches move a lot, wind whistles, umbrellas
             turn inside out.
32-38    Whole trees sway, hard to walk
39-46    Tree twigs break, very hard to walk
47-54    Branches, roof tiles blown down
55-63    Trees uprooted, severe building damage
64-72    Severe destruction

CORIOLAS EFFECT

WIND/ENERGY ENGINEER

• Read the article; work through the tabs at top of the page
• take notes
• we will discuss this career in class
•  
• Wind
   
  What is wind?
  Wind is air in motion. It is produced by the uneven heating of the earth’s surface by the sun. Since the earth’s surface is made of various land and water formations, it absorbs the sun’s radiation unevenly. Two factors are necessary to specify wind: speed and direction.
  
• What causes the wind to blow?
  As the sun warms the Earth's surface, the atmosphere warms too. Some parts of the Earth receive direct rays from the sun all year and are always warm. Other places receive indirect rays, so the climate is colder. Warm air, which weighs less than cold air, rises. Then cool air moves in and replaces the rising warm air. This movement of air is what makes the wind blow.
•  
  
  What is a windstorm?
  A windstorm is just a storm with high winds or violent gusts but little or no rain.
  
  What is a gust front?
  A gust front is the leading edge of cool air rushing down and out from a thunderstorm. There are two main reasons why the air flows out of some thunderstorms so rapidly. The primary reason is the presence of relatively dry air in the lower atmosphere. This dry air causes some of the rain falling through it to evaporate, which cools the air. Since cool air sinks (just as warm air rises), this causes a down-rush of air that spreads out at the ground. The edge of this rapidly spreading cool pool of air is the gust front. The second reason is that the falling precipitation produces a drag on the air, forcing it downward. If the wind following the gust front is intense and damaging, the windstorm is known as a downburst.
  
  What is a downburst?
  A downburst is created by an area of significantly rain-cooled air that, after hitting ground level, spreads out in all directions producing strong winds. Unlike winds in a tornado, winds in a downburst are directed outwards from the point where it hits land or water. Dry downbursts are associated with thunderstorms with very little rain, while wet downbursts are created by thunderstorms with high amounts of rainfall.
  
  What is a derecho?
  A derecho is a widespread and long-lived windstorm that is associated with a fast-moving band of severe thunderstorms. They can produce significant damage to property and pose a serious threat life, primarily by downburst winds. To be classified as a derecho, the path length of the storm has to be at least 280 miles long. Widths may vary from 50-300 miles. Derechos are usually not associated with a cold front, but a stationary front. They occur mostly in July, but can occur at anytime during the spring and summer.
  
  What is the jet stream?
  The jet stream is a fast flowing, river of air found in the atmosphere at around 12 km above the surface of the Earth just under the tropopause. They form at the boundaries of adjacent air masses with significant differences in temperature, such as of the polar region and the warmer air to the south. Because of the effect of the Earth's rotation the streams flow west to east, propagating in a serpentine or wave-like manner at lower speeds than that of the actual wind within the flow.
  
  
  What is a monsoon?
  A monsoon is a seasonal wind, found especially in Asia that reverses direction between summer and winter and often brings heavy rains. In the summer, a high pressure area lies over the Indian Ocean while a low exists over the Asian continent. The air masses move from the high pressure over the ocean to the low over the continent, bringing moisture-laden air to south Asia. During winter, the process is reversed and a low sits over the Indian Ocean while a high lies over the Tibetan plateau so air flows down the Himalaya and south to the ocean. The migration of trade winds and westerlies also contributes to the monsoons. Smaller monsoons take place in equatorial Africa, northern Australia, and, to a lesser extent, in the southwestern United States.
  
  What are the Santa Ana Winds?
  The Santa Ana winds are strong, extremely dry down-slope winds that originate inland and affect coastal Southern California and northern Baja California. Santa Ana winds blow mostly in autumn and winter, but can arise at other times of the year. They can range from hot to cold, depending on the prevailing temperatures in the source regions, the Great Basin and upper Mojave Desert. The winds are known especially for the hot dry weather (often the hottest of the year) that they bring in the fall, and are infamous for fanning regional wildfires. For these reasons, they are sometimes known as the "devil winds" across Southern California.
  
  What are the global wind patterns?
  The equator receives the Sun's direct rays. Here, air is heated and rises, leaving low pressure areas behind. Moving to about thirty degrees north and south of the equator, the warm air from the equator begins to cool and sink. Between thirty degrees latitude and the equator, most of the cooling sinking air moves back to the equator. The rest of the air flows toward the poles.
  
  
  What are the trade winds?
  The trade winds are just air movements toward the equator. They are warm, steady breezes that blow almost continuously. The Coriolis Effect makes the trade winds appear to be curving to the west, whether they are traveling to the equator from the south or north.
  
  What are the doldrums?
  The doldrums is an area of calm weather. The trade winds coming from the south and the north meet near the equator. These converging trade winds produce general upward winds as they are heated, so there are no steady surface winds.
  
  What are the prevailing westerlies?
  Between thirty and sixty degrees latitude, the winds that move toward the poles appear to curve to the east. Because winds are named from the direction in which they originate, these winds are called prevailing westerlies. Prevailing westerlies in the Northern Hemisphere are responsible for many of the weather movements across the United States and Canada.
  
  What are the polar easterlies?
  At about sixty degrees latitude in both hemispheres, the prevailing westerlies join with the polar easterlies to reduce upward motion. The polar easterlies form when the atmosphere over the poles cools. This cool air then sinks and spreads over the surface. As the air flows away from the poles, it is turned to the west by the Coriolis effect. Again, because these winds begin in the east, they are called easterlies.
  
  What is a sea breeze?
  On a warm summer day along the coast, this differential heating of land and sea leads to the development of local winds called sea breezes. As air above the land surface is heated by radiation from the Sun, it expands and begins to rise, being lighter than the surrounding air. To replace the rising air, cooler air is drawn in from above the surface of the sea. This is the sea breeze, and can offer a pleasant cooling influence on hot summer afternoons.
  
  
  What is a land breeze?
  A land breeze occurs at night when the land cools faster than the sea. In this case, it is air above the warmer surface water that is heated and rises, pulling in air from the cooler land surface.
  
  
  How is wind helpful to Earth?
  Wind is the fastest growing source of electricity in the world. It's often one of the least expensive forms of renewable power available. Some experts say it can sometimes be the cheapest form of any kind of power. Generating power from the wind leaves no dangerous waste products behind. Best of all, its supply is unlimited.
  
  How do windmills work?
  Windmills work because they slow down the speed of the wind. The wind flows over the airfoil shaped blades causing lift, like the effect on airplane wings, causing them to turn. The blades are connected to a drive shaft that turns an electric generator to produce electricity.
  
  
  What are some different types of wind names?
  Many local wind systems have their own names. Here's a few!
  chinook-(westerly wind off the eastern side of the Rocky Mountains)
  santa ana-(easterly towards Southern California )
  scirocco-(southerly from North Africa to southern Europe)
  mistral-(northwesterly from central France to Mediterranean)
  marin-(southeasterly from Mediterranean to France)
  bora-(northeasterly from eastern Europe to Italy)
  gregale-(northeasterly from Greece)
  etesian-(northwesterly from Greece)
  libeccio-(southwesterly towards Italy)
  
  Beaufort Scale
  The Beaufort scale is an empirical measure for the intensity of the weather based mainly on wind power. The scale was created by the British naval commander Sir Francis Beaufort around 1806.

  Beaufort number	Wind speed MPH	Wind Speed Knots	Description	Sea conditions	Land conditions
  0	<1	<1	Calm	Flat	Calm
  1	1-3	1-3	Light air	Ripples without crests	Wind motion visible in smoke
  2	4-7	4-6	Light breeze	Small wavelets	Leaves rustle
  3	8-12	7-10	Gentle breeze	Large wavelets	Smaller twigs in constant motion
  4	13-18	11-16	Moderate breeze	Small waves	Small branches begin to move
  5	19-24	17-21	Fresh breeze	Moderate longer waves	Smaller trees sway
  6	25-31	22-27	Strong breeze	Large waves with foam crests	Large branches in motion
  7	32-38	28-33	Near gale	Sea heaps up and foam begins to streak	Whole trees in motion
  8	39-46	34-40	Gale	Moderately high waves with breaking crests	Twigs broken from trees
  9	47-54	41-47	Severe gale	High waves with dense foam	Light structure damage
  10	55-63	48-55	Storm	Very high waves. The sea surface is white	Trees uprooted. Considerable structural damage
  11	64-72	56-63	Violent storm	Exceptionally high waves	Widespread structural damage
  12	73-82	64-71	Hurricane	Sea completely white with driving spray.	Massive and widespread damage to structure

   

WEATHER - CLOUDS - ANSWERS TO #1-6 QUESTIONS

1. What are clouds?

Clouds are visible collections of tiny water droplets (or ice crystals if it's cold enough) that live high in the atmosphere above the Earth's surface.

2. How do clouds form?

Clouds form when a parcel of air rises from the surface up into the atmosphere. As the parcel ascends, it passes through lower and lower pressure levels (pressure decreases with height). Recall that air tends to move from higher to lower pressure areas, so as the parcel travels into lower pressure areas, the air inside of it pushes outward, causing it to expand. This expansion uses heat energy, and therefore cools the air parcel. The farther upward it travels, the more it cools. When its temperature cools to that of its dew point temperature, the water vapor inside of the parcel condenses into droplets of liquid water. These droplets then collect on the surfaces of dust, pollen, smoke, dirt, and sea salt particles called nuclei. (These nuclei are hygroscopic, meaning they attract water molecules.) It is at this point--when water vapor condenses and settles onto condensation nuclei--that clouds form and become visible.

3. Why do clouds billow and change their shape?

Have you ever watched a cloud long enough to see it expanding outward, or looked away for a moment only to find that when you look back its shape has changed? If so, you'll be glad to know it isn't your imagination. Clouds are ever-changing thanks to the processes of condensation and evaporation.

After a cloud forms, the process that grows it (condensation) doesn't stop. This is why we sometimes notice clouds expanding into neighboring sky. But as currents of warm, moist air continue to rise and feed condensation, drier air from the surrounding environment eventually infiltrates the buoyant column of air, a process called entrainment. When this drier air is introduced into the cloud body, it evaporates the cloud's droplets and causes parts of the cloud to dissipate.

4. Why do clouds float?

Clouds start out high up in the atmosphere because that's where they're created, but the reason why they remain suspended there has to do with the tiny particles they contain.

A cloud's water droplets or ice crystals are very small, less than a micron (that's less than one-millionth of a meter). Because of this, they respond very slowly to gravity. To help visualize this concept, consider a rock and a feather; gravity affects each, however the rock falls quickly whereas the feather gradually drifts to the ground because of its light weight. Now compare a feather and an individual cloud droplet particle; the particle will take even longer than the feather to fall, and because of the particle's tiny size, the slightest movement of air will keep it aloft. Because this applies to each cloud droplet, it applies to the entire cloud itself.

5. How do clouds move?

Clouds travel with the upper-level winds. They move at the same speed and in the same direction as the prevailing wind at the cloud's level (low, middle, or high).

High-level clouds are among the fastest moving because they form near the top of the troposphere and are pushed by the jet stream.

6. How do clouds get their color?

A cloud's color is determined by the light it receives from the Sun. (Recall that the Sun emits white light; that white light is made up of all the colors in the visible spectrum: red, orange, yellow, green, blue, indigo, violet; and that each color in the visible spectrum represents an electromagnetic wave of a different length.)

The process works like this: As the Sun's light waves pass through the atmosphere and clouds, they meet the individual water droplets that make up a cloud. Because the water droplets have a similar size as the wavelength of sunlight, the droplets scatter the Sun's light in a type of scattering known as Mie scattering in which all wavelengths of light are scattered. Because all wavelengths are scattered, and together all colors in the spectrum make up white light, we see white clouds.

In the case of thicker clouds, such as stratus, sunlight passes through but is blocked. This gives the cloud a grayish appearance.

WEATHER - BEAUFORT SCALE

Beaufort Scale - INTERACTIVE

The Beaufort wind scale is a standard scale, running from force 0 for calm to force 12 hurricane and above for the description of wind speed. Each value represents a specific range and classification of wind speeds with accompanying descriptions of the effects on surface features. It was originally developed as a system for estimating wind strengths without the use of instruments. It was introduced in 1806 by Admiral Sir Francis Beaufort (1774-1857) of the British navy to describe wind effects on a fully rigged man-of-war frigate of the period, and it was later modified to include descriptions of effects on land features as well. It is currently still in use for this same purpose as well as to tie together various components of weather (wind strength, sea state, observable effects) into a unified picture. The Beaufort Scale  (for use at sea) FORCE DESCRIPTION SEA STATE SPEED knots m/s 0 calm like a mirror <1 0.0-0.2 1 light air ripples, no foam 1-3 0.3-1.5 2 light breeze small wavelets, smooth crests with glassy appearance 4-6 1.6-3.3 3 gentle breeze large wavelets, some crests break, some white horses 7-10 3.4-5.4 4 moderate breeze small waves, frequent white horses 11-16 5.5-7.9 5 fresh breeze moderate rather long waves, many white horses, some spray 17-21 8.0-10.7 6 strong breeze some large waves, extensive white foam crests, some spray 22-27 10.8-13.8 7 near gale sea heaped up, streaks of foam blowing with the wind 28-33 13.9-17.1 8 gale fairly high and long waves, crests breaking into spindrift, blowing foam in prominent streaks 34-40 17.2-20.7 9 strong gale high waves, dense foam streaks in wind, wave-crests topple and roll over, spray reduces visibility 41-47 20.8-24.4 10 storm very high waves, overhanging crests, dense blowing foam, heavy tumbling sea appears white, visibility poor 48-55 24.5-28.4 11 violent storm exceptionally high waves, hiding small ships, sea covered with foam, crests blown into froth, visibility poor 56-63 28.5-32.6 12 hurricane air filled with foam and spray, sea white, visibility extremely bad >64 32.7

WEATHER - CLOUDS REVIEW

REVIEW:

The Core Four

While clouds appear in infinite shapes and sizes they fall into some basic forms. From his Essay of the Modifications of Clouds (1803) Luke Howard divided clouds into three categories; cirrus, cumulus and stratus.

	Cirro-form The Latin word 'cirro' means curl of hair. Composed of ice crystals, cirro-form clouds are whitish and hair-like. There are the high, wispy clouds to first appear in advance of a low pressure area such as a mid-latitude storm system or a tropical system such as a hurricane.
	Cumulo-form Generally detached clouds, they look like white fluffy cotton balls. They show vertical motion or thermal uplift of air taking place in the atmosphere. They are usually dense in appearance with sharp outlines. The base of cumulus clouds are generally flat and occurs at the altitude where the moisture in rising air condenses.
	Strato-form From the Latin word for 'layer' these clouds are usually broad and fairly wide spread appearing like a blanket. They result from non-convective rising air and tend to occur along and to the north of warm fronts. The edges of strato-form clouds are diffuse.
	Nimbo-form Howard also designated a special rainy cloud category which combined the three forms Cumulo + Cirro + Stratus. He called this cloud, 'Nimbus', the Latin word for rain. The vast majority of precipitation occurs from nimbo-form clouds and therefore these clouds have the greatest vertical height.

Combinations of the Core Four

Based on his observations, Howard suggested there were modifications (or combinations) of these core clouds between categories. He noticed that clouds often have features of two or more categories; cirrus + stratus, cumulus + stratus, etc. His research served as the starting point for the ten basic types of clouds we observe.

We call these CLOUDS:

 Altocumulus, Altostratus, Cirrus, Cirrocumulus, Cirrostratus, Cumulonimbus, Cumulus, Nimbostratus, Stratocumulus andStratus.

By convention, clouds are vertically divided into three levels; low, middle, and high. Each level is defined by the range of levels at which each type of cloud typically appears. Divided by their height the ten types of clouds are...

• Cirrus (Ci), Cirrocumulus (Cc), and Cirrostratus (Cs) are high level clouds. They are typically thin and white in appearance, but can appear in a magnificent array of colors when the sun is low on the horizon.

Cloud Poster. Click to enlarge.
• Altocumulus (Ac), Altostratus (As), and Nimbostratus (Ns) are mid-level clouds They are composed primarily of water droplets, however, they can also be composed of ice crystals when temperatures are low enough.
  
  In Latin, alto means 'high' yet Altostratus and Altocumulus clouds are classified as mid-level clouds. 'Alto' is used to distinguish between liquid-based clouds. They are 'high' relative to their low level liquid-based counterpart clouds Stratus and Cumulus.
  
  Altostratus can extend into the high level of clouds. Nimbostratus can extend into the high level as well but the base of the cloud typically decreases into the low level as precipitation continues.
• Cumulus (Cu), Stratocumulus (Sc), Stratus (St), and Cumulonimbus(Cb) are low clouds composed of water droplets. Cumulonimbus, with its strong vertical updraft, extends well into the the high level of clouds.

"Clouds out my Window" book.

by:  John "Dr. Lightning" Jensenius, a NWS Meteorologist in Maine



TEN BASIC CLOUDS
From the World Meteorological Organization's (WMO) International Cloud Atlas, the official worldwide standard for clouds, the following are definitions of the ten basic cloud types.

High Level Clouds

Cirrus (Ci) Detached clouds in the form of white, delicate filaments, mostly white patches or narrow bands. They may have a fibrous (hair-like) and/or silky sheen appearance. Cirrus clouds are always composed of ice crystals, and their transparent character depends upon the degree of separation of the crystals. As a rule when these clouds cross the sun's disk they hardly diminish its brightness. But when they are exceptionally thick they may veil its light and obliterate its contour. Before sunrise and after sunset, cirrus is often colored bright yellow or red. These clouds are lit up long before other clouds and fade out much later; some time after sunset they become gray. At all hours of the day Cirrus near the horizon is often of a yellowish color; this is due to distance and to the great thickness of air traversed by the rays of light.
Cirrocumulus (Cc) Thin, white patch, sheet, or layered of clouds without shading. They are composed of very small elements in the form of more or less regularly arranged grains or ripples. Most of these elements have an apparent width of less than one degree (approximately width of the little finger - at arm's length). In general Cirrocumulus represents a degraded state of cirrus and cirrostratus both of which may change into it and is an uncommon cloud. There will be a connection with cirrus or cirrostratus and will show some characteristics of ice crystal clouds.
Cirrostratus (Cs) Transparent, whitish veil clouds with a fibrous (hair-like) or smooth appearance. A sheet of cirrostratus which is very extensive, nearly always ends by covering the whole sky. During the day, when the sun is sufficiently high above the horizon, the sheet is never thick enough to prevent shadows of objects on the ground. A milky veil of fog (or thin Stratus) is distinguished from a veil of Cirrostratus of a similar appearance by the halo phenomena which the sun or the moon nearly always produces in a layer of cirrostratus.

Mid Level Clouds

Altocumulus (Ac) White and/or gray patch, sheet or layered clouds, generally composed of laminae (plates), rounded masses or rolls. They may be partly fibrous or diffuse and may or may not be merged. Most of these regularly arranged small elements have an apparent width of one to five degrees (larger than the little finger and smaller than three fingers - at arm's length). When the edge or a thin semitransparent patch of altocumulus passes in front of the sun or moon a corona appears. This colored ring has red on the outside and blue inside and occurs within a few degrees of the sun or moon. The most common mid cloud, more than one layer of Altocumulus often appears at different levels at the same time. Many times Altocumulus will appear with other cloud types.
Altostratus (As) Gray or bluish cloud sheets or layers of striated or fibrous clouds that totally or partially covers the sky. They are thin enough to regularly reveal the sun as if seen through ground glass. Altostratus clouds do not produce a halo phenomenon nor are the shadows of objects on the ground visible. Sometime virga is seen hanging from Altostratus, and at times may even reach the ground causing very light precipitation.
Nimbostratus (Ns) Resulting from thickening Altostratus, This is a dark gray cloud layer diffused by falling rain or snow. It is thick enough throughout to blot out the sun. The cloud base lowers as precipitation continues. Also, low, ragged clouds frequently occur beneath this cloud which sometimes merges with its base.
While Altostratus and Nimbostratus can extend into the high level of clouds, Nimbostratus can extend into the low level as well.

Low Level Clouds

Cumulus (Cu) Detached, generally dense clouds and with sharp outlines that develop vertically in the form of rising mounds, domes or towers with bulging upper parts often resembling a cauliflower. The sunlit parts of these clouds are mostly brilliant white while their bases are relatively dark and horizontal. Over land cumulus develops on days of clear skies, and is due diurnal convection; it appears in the morning, grows, and then more or less dissolves again toward evening.
Cumulonimbus (Cb) The thunderstorm cloud, this is a heavy and dense cloud in the form of a mountain or huge tower. The upper portion is usually smoothed, fibrous or striated and nearly always flattened in the shape of an anvil or vast plume. Under the base of this cloud which is often very dark, there are often low ragged clouds that may or may not merge with the base. They produce precipitation, which sometimes is in the form of virga. Cumulonimbus clouds also produce hail and tornadoes.
Cumulus and Cumulonimbus clouds are usually found in the low level category, but their tops may reach into the mid and high levels.
Stratocumulus (Sc) Gray or whitish patch, sheet, or layered clouds which almost always have dark tessellations (honeycomb appearance), rounded masses or rolls. Except for virga they are non-fibrous and may or may not be merged. They also have regularly arranged small elements with an apparent width of more than five degrees (three fingers - at arm's length).
Stratus (St) A generally gray cloud layer with a uniform base which may, if thick enough, produce drizzle, ice prisms, or snow grains. When the sun is visible through this cloud, its outline is clearly discernible. Often when a layer of Stratus breaks up and dissipates blue sky is seen. Sometimes appearing as ragged sheets Stratus clouds do not produce a halo phenomenon except, occasionally at very low temperatures.

http://www.srh.weather.gov/srh/jetstream/clouds/basicten.htm

CLOUD MATCHING - ACTIVITY