Activity 6: Clouds & Precipitation
CLOUD FORMATION AND PRECIPITATION
There are four main types of clouds and many forms of precipitation. In this activity we will explore cloud formation and precipitation by observing and recording weather data, as well as setting up our own "cloud chamber" to observe evaporated water vapor as it condenses and precipitates.
Instructional Method: Demonstration
Goal: To show students how clouds and rain are formed.
Objectives: Students will be able to:
Lecture- 5 steps of cloud formation (25 min)
Warm, moist air rises from Earth's surface. As it rises it begins to cool, raising the Relative Humidity of the air. When the relative humidity reaches 100%, the air is saturated with water. When this happens, water begins to condense in the atmosphere, and clouds begin to form.
The type of cloud formed is dependent on several weather factors including air temperature, relative humidity, wind speed, and air pollution. Most meteorologists agree that water could stay in the atmosphere as humidity indefinitely. Impurities in the air such as dust, smoke or air pollution attract and hold water molecules together forming large droplets. Clouds form as the air reaches saturation and droplets begin to form around these impurities.
The four main types of clouds are:
As all clouds types form, water droplets bump into each other forming larger water droplets. Eventually, the water droplets become too heavy to remain suspended in the clouds, and gravity pulls them to the surface. This process is called precipitation.
Precipitation occurs in many forms, most commonly rain, but also as snow, sleet, hail and virga (desert rain that evaporates before it hits the ground). Even fog and dew are considered to be precipitation.
In this activity we will explore cloud formation and precipitation by observing and recording weather data, as well as setting up our own "cloud chamber" to observe evaporated water vapor as it condenses and precipitates.
What is happening to the water? From where did the falling water come? How did it get there? What is evaporation? What does it mean to be saturated (see sponge activity in the landform unit for an additional saturation activity)? Does air get hotter or colder as it rises in the earth's atmosphere? How does what we just did in the classroom apply in nature? What happens to precipitation in nature? Where does the water go? What is virga, and how does that happen?
Using the overheads and cloud cards, define each basic type of cloud and explain the characteristics of each. Keep a cloud calendar in the classroom, check the weather outside each day, and identify the types of clouds observed and any significant weather for the day. Write it on the calendar. You can also repeat the activity but add a little salt into the water, and then catch some of the precipitation and taste it. Why isn't it salty?
Which types of clouds do we see most often? Will this change as the season changes? Which types of clouds produce rain? Which clouds are primarily ice crystals and seldom rain? Do we ever see more than one kind of cloud in the sky at the same time? What happens then? What time of day did we see the most clouds? In the afternoon? Why is that? (Lead them back to the idea that heat = evaporation = cloud formation and the afternoon is when it is the hottest.)
Included National Parks and other sites:
Utah Science Core:
Kindergarten Standard 3 Objective 1