Florida Content Standards Grade 6

Transcription

1 Florida Content Standards Grade 6 : Earth Systems and Patterns The scientific theory of the evolution of Earth states that changes in our planet are driven by the flow of energy and the cycling of matter through dynamic interactions among the atmosphere, hydrosphere, cryosphere, geosphere, and biosphere, and the resources used to sustain human civilization on Earth. Description: Students will create rainfall to examine how different amounts of water vapor can create different weather conditions. Student Materials (per group): 8 cups Water Food coloring Ice Additional Teacher Materials: Hot water source Background and Misconceptions: Water is a vital and necessary part of weather on Earth. Water that cycles in between the hydrosphere and the atmosphere is what creates most of the weather conditions we experience. The hydrosphere is defined as the collective amount of water that is in all bodies of water on Earth. It can pass into the atmosphere by evaporation. Evaporation occurs when water molecules jump from the liquid into the gaseous phase. Water vapor is not visible. About 4% of the atmosphere is composed of water vapor. Lets follow the path of a molecule of water as it goes from the hydrosphere into the atmosphere and back: The water molecule starts out in body of water, such as an ocean or lake. Eventually, that molecule is able to bounce its way to the surface of the ocean. Then, once at the surface it is able to make the leap into the atmosphere through a process called evaporation. It then is part of the atmosphere where is moves around easily. On occasions, the water molecule starts

2 : Earth Systems and Patterns to join other molecules to form larger droplets. These droplets form easily on dust and other small particles in the atmosphere. Colder temperatures farther up in the atmosphere cause the water to join with other molecules and they all start to condense. This is the formation of clouds. When the clouds form large enough droplets, the upward air currents are no longer able to support them, and they fall back to the ground in the form of rain, snow, or hail. From there, once the land in a body of water, they become part of the hydrosphere once again, where the process starts over. Weather conditions are different depending how a place is located near a body of water or other factors. Florida is particularly susceptible to the effects of heat and the massive evaporation of water because it is almost completely surrounded by water. That factor alone makes Florida a moist subtropical environment. However, examine a world map. Most of the world s great deserts are located at the same latitude as Florida. Were it not for the Gulf of Mexico and the Atlantic, Florida would likely be a desert as well. This alone shows the power of water as it cycles in and out of the atmosphere. The atmosphere can hold more water when it is warmer than in cooler northern climates. Florida s absolute humidity is higher than the absolute humidity in the northern US. Absolute humidity differs from relative humidity in that relative humidity is the amount of water in the atmosphere at a given temperature. In other words, it is temperature dependent. Absolute humidity is the raw amount of water contained in the air and is not temperature dependent. So, in general the more water in the air at a given temperature, the more rainfall that will occur. Low levels of humidity will generally occur over the deserts and dryer regions. It is important to point out that even a generally dry area can be inundated with rainfall. Weather is the term we apply to day to day changes in the atmosphere. However, climate is the general trend of weather that occurs over a long period of time. So the desert southwest has a climate that is hot and dry, with little rainfall. But a weather event may occur that could cause massive amounts of rainfall. Mark Twain once said: Climate is what we expect, weather is what we get!

3 : Earth Systems and Patterns In this experiment, food color is added to the water so that students will see that only water evaporates and condenses on the inside of the cups. The ice aids in the formation of droplets and rain. The room temperature cups are more synonymous with dryer or cooler regions where there is less rainfall. After the lesson make the connection between how much water cycles in and out of the atmosphere and how it impacts weather and climate. Teacher Guided Questions to Inquiry: Use these questions to get the students started on their own inquiry! How does humidity affect weather/ What is the difference between weather and climate? How does the amount of water vapor in the atmosphere affect the weather in a particular area? Why are some areas of earth dry and others wet? Additional Hints: A large aquarium can be used to further discuss the water cycle and how rain can fall in one area and be transported from another body of water. Be sure to discuss the water cycle and compare with weather and climate.

4 4 : Earth Systems and Patterns TEACHER ANSWER KEY Description: The cycling of water from the hydrosphere and the atmosphere is an important part of what drives and affects the weather and general climate patterns. In this experiment, you are going to model the effect of evaporation and condensation in several climate conditions. Materials: 8 Clear Cups Food Color Hot water Ice Cubes Procedures: 1. Into 2 cups, pour hot water. Fill up about ½ way. 2. In 2 additional cups, pour room temperature water. You will now have 4 cups total. 3. Place a couple of drops of food coloring in the water. 4. Place the second cup on top of the first, so that it is upside down. Do this as the same time for each cup. 5. On one cup, place an ice cube. 6. Record what you see in the table below.

5 : Earth Systems and Patterns Observations Observations Cups with no ice on top, hot water Moisture collected throughout the top of the cup. Some drops ran back into the cup. The droplets were all clear (not colored from the food coloring.) Cups with no ice on top, room temperature water There was very little condensation. Cups with ice on top, hot water Lots of water condensed under the ice and they dripped back into the water. The droplets were all clear. Cups with ice on top, room temperature water. There may have been small amounts of condensations, but not as much as the hot water cups. 1. Questions: In the cups with hot water, when did more water collect inside the cups? Explain why. When the cups had ice on the top. The ice causes the water vapor to cool and condense. 2. What part of this experiment demonstrates rainfall? When drops of water fall back into the cup. The most drops occurred under the cups with the ice. 3. How do you know that only water was evaporating from the cups? The condensed water was clear. Those drops were not the same color as the food coloring.

6 : Earth Systems and Patterns 4. From this experiment, in which areas on Earth will there be more rainfall? In warm humid areas. 5. What influences the amount of rainfall that occurs in different areas? The amount of water vapor in the atmosphere. Dryer deserts have less rain than humid warm regions. 6. Below, draw a picture of the water that cycles in this experiment and label the parts.

7 : Earth Systems and Patterns Name Date Description: The cycling of water from the hydrosphere and the atmosphere is an important part of what drives and affects the weather and general climate patterns. In this experiment, you are going to model the effect of evaporation and condensation in several climate conditions. Materials: 8 Clear Cups Food Color Hot water Ice Cubes Procedures: 1. Into 2 cups, pour hot water. Fill up about ½ way. 2. In 2 additional cups, pour room temperature water. You will now have 4 cups total. 3. Place a couple of drops of food coloring in the water. 4. Place the second cup on top of the first, so that it is upside down. Do this as the same time for each cup. 5. On one cup, place an ice cube. 6. Record what you see in the table below.

8 8 : Earth Systems and Patterns Observations Cups with no ice on top, hot water Cups with ice on top, hot water Observations Cups with no ice on top, room temperature water Cups with ice on top, room temperature water. 1. Questions: In the cups with hot water, when did more water collect inside the cups? Explain why. 2. What part of this experiment demonstrates rainfall? 3. How do you know that only water was evaporating from the cups?

9 : Earth Systems and Patterns 4. From this experiment, in which areas on Earth will there be more rainfall? 5. What influences the amount of rainfall that occurs in different areas? 6. Below, draw a picture of the water that cycles in this experiment and label the parts.