Water Cycle & Cloud Types Unit:



Water Cycle & Cloud Types Unit:

An Introduction to Weather and Climate

This unit is designed to prepare students for a more in-depth discussion about global climate change and human impact on environmental systems related to climate (hydrologic cycle, oceanic and atmospheric pollution, greenhouse effect, etc.)

Scope of unit is (4-5) 50 minute class periods.

Sources

Lesson plan created by and resources compiled by Shirley Tremel









Target Grades 6-8

Goals and Purpose of Unit

• Students will be able to identify the three main elements of the hydrologic cycle and discuss the importance of the cycle on healthy ecosystem function.

• Students will describe characteristics of different cloud types and where they occur in the atmosphere.

• Students will be able to describe the differences between weather and climate.

• Students will be better prepared for a more advanced unit on climate change.

List of Topics Covered in Unit

• Hydrologic Cycle

• Cloud Types and Precipitation

• Introduction to Climate

• Climate vs. Weather

• Weather Predictions/Meteorology

Plan of Action

• Introduce Hydrologic Cycle (water cycle) and discuss environmental significance. (PowerPoint presentation and link to water cycle tutorial below)

• Activity on water cycle, if time permits. (There is one in the same unit as Activity 1, and others provided in the additional background links)

• After water cycle lecture, discuss the classification and formation of clouds, and their impact on the weather.

• Cloud types activity (Activity 1)

• Introduction to Climate (see background information in this unit and refer to links provided below)

• Now that students know a bit more about climate, how is that different from the weather we experience in our daily lives? Weather vs. Climate

• Weather predictions inquiry activity (Activity 2)

• Synthesis of how the water cycle, cloud formation and precipitation, short-term weather, and long-term climate trends are all closely related.

Activity 1: Cloud Types

• “It’s Time to Get Cirrus With Clouds” taken from:



Activity 2: Meteorology Guided Inquiry

Provided with unit, taken from NASA’s Meteorology: An Educator's Resource for Inquiry-Based Learning for Grades 5-9

• “Predicting Weather by Connecting the Basic Cloud Types With Information Collected from the Weather Station”

Links for Additional Background Information and Lesson Plans

(water cycle tutorial)

(summary)

mission_pages/noaa-n/climate/climate_weather.html

(weather vs. climate)

lessons/water-cycle.cfm

(climate change and water cycle lesson plans)

(introduction to climate)

(activities for the classroom)





(an excellent resource!)

Materials Needed for Class of 30 students

Activity 1:

• altitude chart--(included)

• cloud chart--(included)

• cotton balls--3 bags @ $1.29 each...........$3.87

• sheet cotton--

• glue--

• markers--

• black construction paper--

Science Standards Addressed

• 6.2.ES.1 Explain the water cycle.

• 8.2.ES.4 Explain what causes patterns of atmospheric and oceanic movement and how these movements affect weather and climate

• 7.2.ES.2 Evaluate factors that affect global environmental change and suggest and evaluate possible solutions to problems

• Scientific Inquiry standards for grades 6,7,8.

Unit Extensions

Many of the NASA links provided above include activities that require students to do research and gather data from the NASA website. A student-initiated project allows students to take on one aspect of either the NASA data collection activity or one of the other inquiry activities listed above and to expand their knowledge based on their individual interests.

Assessment

Ask students to complete journals or build portfolios to see their progress over time and to allow space for student questions.

Background Information

Hydrologic Cycle ()

The water cycle, also known as the hydrologic cycle, describes the continuous movement of water on, above, and below the surface of the Earth. Since the water cycle is truly a "cycle," there is no beginning or end. Water can change states among liquid, vapor, and ice at various places in the water cycle. Although the balance of water on Earth remains fairly constant over time, individual water molecules can come and go.

The Hydrologic Cycle and Clouds (Meteorology: An Educator's Resource for Inquiry-Based Learning for Grades 5-9)

The water cycle describes the condensation of water vapor and the formation of cloud droplets and eventually precipitation in rising air masses. The three main elements of the water cycle are evaporation, condensation and precipitation. Evaporation is the process of transforming liquid water in the oceans and in the soil to water vapor, an invisible, odorless gas that enters the atmosphere. Condensation is the process of changing gaseous

water vapor back to liquid water and in the process forming cloud droplets. As the water vapor rises in the atmosphere, atmospheric temperature decreases with altitude and condensation begins, resulting in the formation of tiny cloud droplets. The tiny cloud droplets begin to collide and coalesce with neigh-boring cloud droplets, growing in size and weight and eventually forming precipitation, which “falls” out of the atmosphere as liquid water droplets (rain) or solid water particles (snow and hail). Other processes in the water cycle are freezing, melting and sublimation, which all involve changing the state of water. Sublimation is the change of phase from a solid to a gas without the intermediate step of forming liquid. In the case of water, sublimation is the change from snow or ice to gaseous water vapor, without the intermediate step of forming liquid water.

Cloud condensation nuclei (CCN) are very small particles (typically about 1/100th the size of a cloud droplet) upon which cloud droplets coalesce. To make a transition from the gaseous state of water vapor to the liquid water droplet, a nongaseous

surface is required. In the atmosphere, tiny solid or liquid CCN particles provide this surface.

Clouds are visible masses of condensed droplets or frozen crystals suspended in the atmosphere above the surface. Clouds are divided into two main categories: convective or cumulus clouds (in Latin, cumulus means piled up) and layered or stratus clouds (in Latin, stratus means layer). Cumulus and stratus clouds are divided into four more groups that distinguish the altitude location of the cloud. The family of low clouds (found up to 2 km (6,500 ft)) includes stratus, nimbostratus, cumulus, and stratocumulus. Cumulus clouds (Figure 2-9) are dense, white and puffy, resembling cotton balls. Cumulus clouds are found either as single clouds or closely packed clouds. While cumulus clouds resemble puffy white cotton balls and are associated with good weather, stratus clouds (Figure 2-10) are dark gray, low, uniformly stratified or layered covering the entire sky and are usually associated with rain. Middle clouds are found between 2 and 5 km (6,500 and 16,500 ft). Middle clouds are denoted by the prefix “alto” and include altostratus and altocumulus. High clouds are found above 5 km (16,500 ft) in the cold region of the troposphere and are denoted by the prefix “cirro” or cirrus. At this altitude, water freezes so the clouds are almost always composed of ice crystals. These clouds are wispy and often transparent. High clouds include cirrus, cirrostratus and cirrocumulus. Aircraft contrails form in this altitude range. Vertical clouds have strong upward currents and form over a wide altitude range and include cumulonimbus, which are very large, towering dark clouds usually associated with heavy precipitation and thunderstorm activity.

Effects of Hydrologic Cycle on Climate ()

The water cycle is powered from solar energy. 86% of the global evaporation occurs from the oceans, reducing their temperature by evaporative cooling. Without the cooling effect of evaporation the greenhouse effect would lead to a much higher surface temperature of 67 °C (153 °F), and a warmer planet

Climate ()

Climate refers to the long-term changes in atmospheric conditions including temperature, rainfall, wind, humidity, pressure and cloudiness. One would need to take into account the fact that superimposed on the arithmetical average of these parameters, there is generally experienced a seasonal oscillation, perhaps more noticeable in the higher latitudes. It is therefore necessary to take the seasonal patterns as a unit of measurement and to consider climate to be represented by the long-term average of the seasonal cycle over a number of years.

In reality, the meteorological conditions do not remain stable over long periods, and they are forever exhibiting fluctuations and disturbances about the seasonal cycle in time scales of hours and days. It is helpful to consider these short-term changes as Weather.

While acknowledging the presence of the seasonal cycle, Weather might be described as the discrepancies of atmospheric conditions from the expected seasonal situation. In similar terms, Climate might be described as the long-term statistical average of the seasonal cycles.

However, should long-term patterns of those discrepancies be verified, there is then implied a trend, or a change in climate. This might take the form of a gradual drift in temperature such as is envisaged in response to global warming in a greenhouse scenario. Alternatively, the trend might take the form of an increase in the incidence of severe weather, as for example in the frequency of occurrence of tropical cyclones. This also is a condition, which might be associated by some as an indicator of global warming.

In its most simple form, one might claim the following:

• Climate is what can be expected

• Weather is what is actually experienced

• Climate Change is represented by a long-term trend in either case.

The longer the time scale, the greater the need to broaden the spatial scale of interest, since there is more likelihood of complex large-scale interactions of the world's atmosphere and ocean, snow and ice cover, the state of the land surface and its vegetation.

In the Pacific, many islands experience a hot, wet season and a cooler, drier season, but there are many short-term departures from these general themes.

Different Climates

The earth's climate varies from place to place. Locations near the Equator tend to be constantly hot and wet, such as the Pacific islands and the Amazon Basins. Some places near the North and South Poles, such as Antarctica and Greenland, are extremely cold and dry.

Amount of Solar Radiation

The main cause of the variation of temperature is the amount of solar energy that is received (Module One, Seasons). In general, in higher latitudes further away from the Equator, less solar radiation is received and the lower the temperature experienced.

On a global scale, the amount of energy received from the Sun is much greater in the Southern Hemisphere during December and January each year and much less during June and July. In the Northern Hemisphere, radiation is greater during June and July and less during December and January.

Altitude

The altitude (height) of a place also affects the temperature. As shown already in Module One, the ground receives solar radiation and then heats the air above it by long-wave radiation, conduction, and convection. So the closer to the earth's surface, the warmer the temperature of the air. The temperature decreases with height in the troposphere at a rate of 6.5 degrees for every 1000 meters. This is why glaciers can be found in Papua New Guinea, although it is very close to the Equator.

Distance from the Sea

The distance from the sea affects the temperature. Land has a lower specific heat capacity (i.e., amount of heat energy required to raise the temperature of a unit mass by 1 degrees Celsius) than water; it heats up more quickly during the day than the sea and loses its heat more quickly at night. During the summer season, the interior of a large island or land mass becomes much hotter than coastal areas, which are kept cooler by the sea. During the winter season, areas that are inland get cooler than those close to the sea during the day and vice versa at night. Because most Pacific islands are very small, the temperatures during summer (December and January) are not as hot as those in the middle of Australia, which is further south but a long way from the sea.

Cloud Cover

Cloud cover affects temperature (slightly more detail of clouds is explained in the following section of this module). Thick clouds reflect incoming solar radiation by day and also prevents much of the long-wave ground radiation by night from leaving the lower layers of the troposphere. So, cloudy conditions cause lower temperatures by day and higher temperatures by night.

Type of Ground Surface

The type of surface also affects the temperature. Areas that are covered in ice and snow reflect almost all of the incoming solar radiation and cannot benefit to the same degree as darker surfaces. Sandy beaches may reflect up to half of all the solar energy received, particularly if they are composed of white sand. In contrast, dark surfaces such as forests will absorb most of the incoming radiation, and temperatures above them will be higher than over light-colored surfaces. As one may be aware, this makes white cars more heat tolerant.

................
................

In order to avoid copyright disputes, this page is only a partial summary.

Google Online Preview   Download