Cloud Formation and Weather Prediction

Author: Kevin Petrak
Secondary Science Teacher
35 Mathews Ave #31, Waterville
(207) 873 0822
kpetrak@juno.com
Messalonskee High School

Weather Prediction
Overview : The teacher will demonstrate the concept of weather prediction based upon continuous observation and recording.  Students will be able to predict what type of weather corresponds with specific types of clouds.

Objective: The student will be able to predict precipitation based on the type of cloud currently present outside.

Grade Levels: 7-9 Physical and Earth sciences

Maine Learning results objectives:
Science and Technology
F.  The Earth - Students will gain knowledge about the earth and the processes that change it.  Students will be able to describe how air pressure, temperature, and moisture interact to cause changes in the weather.
J.   Inquiry and Problem Solving - Students will apply inquiry and problem-solving approaches in science and technology.  Students will be able to make accurate observations using appropriate tools and units of measure.
J. Inquiry and Problem Solving - Students will apply inquiry and problem-solving approaches in science and technology.  Students will be able to verify, evaluate, and use results in a purposeful way.  This includes analyzing and interpreting data, making predictions based on observed patterns, testing solutions against the original problem conditions, and formulating additional questions.

Materials & Resources:
ITV Web Site - http://weather.itv.ca/cloudchart/cloudguide.html

Main Ideas:
1.  Fronts and Air Masses - how they move through the country (mostly west to east)
a.  Warm fronts
b.  Cool fronts

2.  Types of clouds which accompany precipitation
a.  Cumulonimbus - thunderstorm cloud
b.  Stratus - light mist or drizzle
c.  Nimbostratus - continuous rain or snow

3.  Types of clouds which do not accompany precipitation
a.  Cirrus
b.  Cirrostratus
c.  Cirrocumulus
d.  Altostratus
e.  Altocumulus
f.  Stratocumulus
g.  Cumulus

Assignment:
Have students produce a journal of cloud observations and types for different times during the day.  After the pattern recognition (probably a couple weeks), have students predict what type of weather will be occurring when school gets out that afternoon.

Hydrological Cycle
Overview
The teacher will demonstrate the concept of the hydrologic cycle and how it relates to cloud formation.  The ideas of precipitation, evaporation, and condensation will be presented.  Understanding will be exhibited by a diagram of the hydrologic cycle.

Objective: The student will be able to understand the processes behind the formation of clouds.

7-9 Physical and Earth sciences

Maine Learning Results objectives:
Science and Technology
F.  The Earth - Students will gain knowledge about the earth and the processes that change it.  Students will be able to describe how air pressure, temperature, and moisture interact to cause changes in the weather.
L. Communication - Students will communicate effectively in the application of science and technology.  Students will be able to make and use appropriate symbols, pictures, diagrams, scale drawings, and models to represent and simplify real-life situation and to solve problems.

Main Ideas:
1.  Precipitation - falling of water in the forms of rain, snow, or hail
2.  Evaporation - transformation of liquid water into water vapor
a.  steam over a pot of boiling water
b.  "haziness" of a humid day
3.  Condensation - water vapor changes back to liquid
a.  water on the outside of a can of soda (out of the refrigerator)
b.  formation of clouds

Materials & Resources:
Intellicast Web Site - http://www.intellicast.com/DrDewpoint/wx101/0599Clouds/
The hydrological cycle

Assignment:
Have students produce a diagram of the hydrologic cycle and demonstrate how clouds are formed.

Cloud Types:

Overview: The teacher will demonstrate the different types of clouds and how they are classified.  The teacher should include the history of how clouds are named and the main types of classification (derived from Latin).  The teacher will also use web resources as an aid to visualize the different cloud types.

Grade Levels: 7-9 Physical and Earth sciences

Objective:The student will be able to identify different types of clouds.

Maine Learning Results objectives:
Science and Technology
J.  Inquiry and Problem Solving - Students will apply inquiry and problem-solving approaches in science and technology.  Students will be able to make accurate observations using appropriate tools and units of measure.

Materials & Resources:
Intellicast Web Site - http://www.intellicast.com/DrDewpoint/wx101/0599Clouds/
Plymouth State College Web Site - http://vortex.plymouth.edu/clouds.html
University of Illinois Web Site - http://ww2010.atmos.uiuc.edu/(Gh)/guides/mtr/cld/cldtyp/home.rxml

Main Ideas:
1.  High Clouds - Cirrus, Cirrostratus, and Cirrocumulus

2.  Middle Clouds - Altostratus, Altocumulus

3.  Low Clouds - Stratus, Statocumulus, Nimbostratus

4.  Clouds with vertical development - Cumulus, Cumulonimbus

5.  Other clouds which don't fit in a classification category - contrail, mammatus, lenticular, noctilucent, and nacreous.

Classification of Clouds
Clouds are classified using the Latin system developed by Luke Howard, an English naturalist, who described clouds as they would appear to a ground observer.  He classified four basic types of clouds:

Stratus (Latin for "layer") - a sheet-like cloud

Cumulus ("heap") - a puffy cloud

Cirrus ("curl of hair") - a wispy cloud

Nimbus ("violent rain") - a rain cloud

Howard's work was later expanded by Abercromby and Hildebrandsson in 1887.  These scientists identified the clouds by the height of the cloud's base above the surface.  The four major cloud groups and their types along with the abbreviations for the clouds are shown below.

 1.  High Clouds         Cirrus (Ci)         Cirrostratus (Cs)         Cirrocumulus (Cc) 2.  Middle Clouds         Altostratus (As)         Altocumulus (Ac) 3.  Low Clouds         Stratus (St)         Stratocumulus (Sc)         Nimbostratus (Ns) 4.  Clouds with Vertical Development          Cumulus (Cu)         Cumulonimbus (Cb)

High clouds range in height from 16,000 to 60,000 ft (5000 to 18,000 m) depending on the latitude region.  Middle clouds range in height from 6500 to 26,000 ft (2000 to 8000 m).  Low clouds range in height from the surface to 6500 ft (0 to 2000 m).

High Clouds
Cirrus (Ci) clouds are thin, wispy clouds blown by high winds into long streamers.  They usually move from west to east, indicating the prevailing winds at their elevation.  (Fig. 1)

Figure 2 Cirrus Click for larger image

Cirrocumulus (Cc) clouds appear as small, rounded, white puffs, which occur individually or in long rows.  If they appear in rows, a rippling effect is evident which distinguish this type of cloud.  (Fig. 2)

Figure 2 Cirrocumulus click for larger image

Cirrostratus (Cs) clouds are the thin, sheet-like clouds that often cover the entire sky.  Often times, a halo may be seen around the sun and moon when these clouds are present. (Fig 3)

Figure 3 Cirrostratus Click for larger image

Middle Clouds

Altocumulus (Ac) clouds appear as gray, puffy masses.  They often appear in parallel waves or bands.  (Fig. 4)

Figure 4 Altocumulus clouds Click for larger image

Altostratus (As) clouds are gray or blue-gray that covers the sky over an area that stretches over many hundreds of square kilometers.  If objects are not casting shadows, it's a good bet that the cloud is an altostratus.  (Fig. 5)

Figure 5 Altostratus clouds

Low clouds
Stratus (St) clouds are uniform grayish clouds that generally cover the entire sky.  A light mist or drizzle sometimes accompanies stratus.  (Fig. 6)

Figure 6 Stratus clouds Click for larger image

Stratocumulus (Sc) clouds appear as a low, lumpy cloud layer.  They differ from altocumulus in that they have a lower base and are larger.  (Fig. 7)

Figure 7 Stratocumulus clouds Click for larger image

Nimbostratus (Ns) clouds are dark gray cloud layers associated with falling rain or snow.  They are low-lying and sheet-like. (Fig. 8)

Figure 8 Nimbostratus clouds Click for larger image

Clouds with Vertical Development
Cumulus (Cu) clouds are often associated with cotton because of the way they look.  The base of the cloud is often gray and flat.  The cloud may appear to be only a few thousand feet above the surface of the earth and a half-mile wide.  (Fig. 9)

Figure 9 Cumulus clouds Click for larger image

Cumulus congestus clouds are what form after cumulus clouds and resembles a head of cauliflower.  It usually forms a single cloud but may often form a line of towering clouds.  Any precipitation from this type of cloud is showery.  (Fig. 10)

Figure 10 Cumulus congestus clouds Click for larger image

Cumulonimbus (Cb) clouds are thunderstorm clouds.  They often take the shape of an anvil.  (Fig. 11)

Figure 11 Cumulonimbus clouds Click for larger image

Other clouds
Noctilucent clouds appear bright and mean "luminous night clouds".  They are usually observed at high latitudes, at altitudes between 75 and 90 km above the earth's surface.  (Fig. 12)

Figure 12 Noctilucent clouds Click for larger image

Mammatus clouds are baglike sacks that hand beneath a cloud and resemble a cow's udder.  (Fig. 13)

Figure 13 Mammatus clouds Click for larger image

Lenticular clouds form in a wave crest as moist air rises over a mountain.  They usually form in the shape of a lens, which is how the name was derived.
(Fig. 14)

Figure 14 Lenticular clouds Click for larger image

Contrails (condensation trail) are clouds which form behind aircraft from the water vapor added to the air from engine exhaust. (Fig. 15)

Figure 15 A contrail Click for larger image

Soft, pearly looking clouds are called nacreous clouds.  They are best seen in polar latitudes during the winter months when the sun illuminates them because of their high altitude.  (Fig. 16)

Figure 16 Nacreus clouds Click for larger image

Assignment:
Have students describe characteristics of the different types of clouds.  Have students identify the type of clouds which are currently present outside the classroom.

This curiculum project was funded by the Colby Partnership for Science Education, the Howard Hughes Medical Institute,and the Bell Atlantic Foundation.