Exploring Water, Air, and Weather
The Water
Cycle
Humidity &
Reasons for
the Seasons
How people affect
water, air and
weather.
What is evaporation?
Evaporation is the process by which water goes into the
air, changing from a liquid to a gas or vapor.
When do we see this in real life?
• When you boil water do you ever
notice the steam coming out of
the pot?
You are witnessing evaporation!
Evaporation after a rainstorm.
Rate of Evaporation
3
2
Container in the Shade
Container in the Light
1
0
O minutes
15 minutes
Container in the Shade
O minutes
Container in the Light
3
3
15 minutes
3
2
Two dishes were each filled with three teaspoons of water, one dish is placed under a light source and the
other is placed in the shade. After 15 minutes the dish under the light had two teaspoons of water in it, the
dish in the shade still had three. We found that the water evaporated at a rate of one teaspoon per 15
minutes.
What is condensation?
Condensation is the process by which water
vapor in the air is changed into liquid, it is
responsible for the formation of clouds.
Where does this occur in the world?
• If you wear glasses and go from
the cold outdoors to the warm
indoors, the lenses fog up as small
water droplets coat the surface.
• What about the beads of water
that collect on a cold glass of liquid
In the summer? Condensation!
What about precipitation?
Precipitation is water released from clouds in the form
of rain, freezing rain, sleet, snow, or hail. Most
precipitation falls as rain.
Did you know…
• For precipitation to happen, first
tiny water droplets must condense
on even tinier dust, salt, or smoke
particles, which act as a nucleus.
• The common raindrop is actually
shaped more like a hamburger bun.
The Water Cycle in Motion
Click the link below for a musical interlude!
Water Cycle Boogie Music Video
What is humidity?
It is the amount of water vapor that exists in a
gaseous mixture of water and air.
Have you ever heard someone say, “it’s not the heat
it’s the humidity?”
•High humidity makes people feel hotter outside because it reduces the effectiveness
of sweating which helps to cool the body. This prevents the evaporation of
perspiration from the skin, making us feel “sticky.”
Is there a relationship between the temperature outside and
the humidity?
•Of course there is! The hotter the air, the more water it contains. When the
air is full of moisture, there is a high level of humidity.
How do we know how much humidity is in the air?
•Absolute humidity is the quantity of water in a particular
volume of air, measured in cubic meters. The amount of vapor that can
be contained in a cube of air is the absolute humidity in that cubic meter
of air.
How do we know how much humidity is in the air?
•Absolute humidity is the quantity of water in a particular
volume of air, measured in cubic meters. The amount of vapor that can
be contained in a cube of air is the absolute humidity in that cubic meter
of air.
•
How does absolute humidity help weather
forecasters?
Absolute humidity is needed to find the
relative humidity. Relative humidity helps
weather forecasters determine the possibility of
precipitation. A reading of 100% relative humidity
means the air is completely saturated with water
vapor and cannot hold anymore, which means that
it might rain. If the relative humidity near the
ground is much less than 100%, it probably won’t
rain.
To understand relative humidity
take a look at this picture:
The Reasons for the Seasons
• As the Earth rotates, it’s tilted at about a 23.5
degree angle, instead of being straight up and
down like a spinning top.
• This changes the angle at which sunlight hits
the surface as Earth makes its yearly journey
around the Sun.
The Reasons for the Seasons (cont’d)
•The Northern Hemisphere (the one we live in),
gets more sunlight when Earth is tipped toward
the Sun, so it’s hotter (summer).
•At the same time, the Southern Hemisphere
is tilted away from the Sun. The sunlight
spreads out more thinly over a greater area
there, so it’s colder (winter).
•The differences in air temperature help
create our different seasons.
How do People Effect Air, Water, and Weather?
•Whenever we watch television, drive a a car, or play video games, we effect
air, water, and weather.
•These things burn fossil fuels (oil, coal, and gas) to make them work, which puts
more carbon dioxide into the atmosphere, making the Earth warmer! Scientists
call this Global Warming. Check out this video to see how we effect the
weather!
•A warmer Earth may lead to changes in rainfall patterns, a rise in sea level,
and a wide range of impacts on plants, wildlife, and humans.
Searching for the Ways People Effect Air, Water, and
Weather
Scavenger Hunt
• Where does our water supply come from and how does all
that water get to a city of 8 million people?
Find out by searching for a movie on “Our Water Supply” at our
Filamentality Web site Water, Air, and Weather at:
http://www.kn.att.com/wired/fil/pages/listwaterala.html
• What are the three sources of air pollution?
Find out at http://www.sparetheair.org/teachers/bigpicture/IIIA2.html
• What items in your house make air quality better? What
items in your house make air quality worse?
Play the “Clean Air Challenge Game” to become an air quality leader!
http://www.sparetheair.org/teachers/bigpicture/IIIF1a.html
Scavenger Hunt (keep searching!)
• What is the Greenhouse Effect?
To find out go to http://epa.gov/climatechange/kids/greenhouse.html
• How do people contribute to Global Warming?
Find out by searching for a movie on climate change on our Filamentality Web site:
http://www.kn.att.com/wired/fil/pages/listwaterala.html
• How does Global Warming effect the Water Cycle?
Click here to find out:
http://epa.gov/climatechange/kids/water_cycle_version2.html When you’re
done, take the quiz to test your knowledge on how Global Warming effects the
Water Cycle!
The Hunt Goes On!
• What are four things that could be affected by climate
change?
Go to http://epa.gov/climatechange/kids/bigdeal.html to find
out!
• What is the air pollution like in our city right now?
Record the level of Fine Particles and Ozone, our
Temperature, Humidity, and Wind by clicking on the city we
live in at: http://www.hazecam.net/
Scavenger Hunt (the hunt goes on!)
• What is deforestation and how does it affect
the climate?
Find out at http://www.weatherwizkids.com/climate.htm
• What are the causes of acid rain and how does it get carried
around?
Read the “Tale of Lucy Lake” to discover these answers by clicking here
http://www.epa.gov/acidrain/education/site_kids/lucy/1.htm
The End