Unit 2: Atmospheric Science

1. Unit 2: Atmospheric Science

2. Weather and Atmosphere • What is the Weather? • Anyone looking outside notices right away whether it is cloudy or clear. • From personal experience, people know that cloudy skies bring cooler temperatures. Dark clouds often bring rain. Strong winds and blowing snow mean either heavy coats and boots or a day spent indoors!

3. Weather is the state of the atmosphere at a given time and place. • A complete description of the weather includes the amount and type of clouds. • Rain, snow, thunderstorms, lightning, and even dust storms are part of the weather. • Measurements of temperature, pressure, wind speed and direction, and the amount of moisture in the air are also included in a description of the weather.

4. Weather is studied and predicted by scientists called Meteorologists. • The science of Meteorology is the study of the entire atmosphere, including its weather. • To understand and predict the weather, meteorologists must first understand how the atmosphere heats and cools, how clouds form and produce rain, and what makes the wind blow.

5. The Beaufort Scale • Relates wind speed to its effects.

6. The temperature cannot be guessed accurately, but people feel heat and cold. • In the winter, people feel colder when the wind is blowing. The actual temperature can be converted into the temperature the body feels using a chart for the Wind-chill factor. • This adjusted temperature describes the danger of frostbite. In the winter, weather broadcasts often include temperature adjusted for wind-chill.

7. Increased humidity makes wavy and curly hair curlier. High temperatures seem hotter and low temperatures colder when the air is more humid. • Air pressure cannot be felt, but changes in air pressure can. The most common effect of pressure change is the “popping” of the ears. • Ear popping occurs during takeoff or landing of an airplane, a ride in a rapid elevator, or even a ride in a car over a high mountain pass. • In all cases, the ears pop because the air pressure falls with height.

8. Atmospheric Basics • Why is the Atmosphere important? • Why is Earth the only planet in the solar system known to have life? • The main reason is Earth’s atmosphere. • Organisms need the gases in the atmosphere to live. • Water is also essential for life. Water vapor is one of the gases in the atmosphere. Green algae seen above is an example of primitive life that is dependent on water.

9. The Atmosphere is a mixture of gases that surrounds the planet. We also call it air. • The gases in the atmosphere include nitrogen, oxygen, and carbon dioxide. • Along with water vapor, the atmosphere allows life to survive. Without it, Earth would be a harsh, barren world. • We are lucky to have an atmosphere on Earth. The atmosphere supports life and is also needed for the water cycle and weather. The gases of the atmosphere even allow us to hear.

10. The Atmosphere and Living Things • Most of the atmosphere is nitrogen, but it doesn't do much. Carbon dioxide and oxygen are the gases in the atmosphere that are needed for life. • Plants need carbon dioxide for photosynthesis. They use sunlight to change carbon dioxide and water into food. The process releases oxygen. Without photosynthesis, there would be very little oxygen in the air. • Other living things depend on plants for food. These organisms need the oxygen plants release to get energy out of the food. Even plants need oxygen for this purpose.

11. The Atmosphere and the Sun’s Rays • The atmosphere protects living things from the sun’s most harmful rays. Gases reflect or absorb the strongest rays of sunlight. The atmosphere shields Earth from the most harmful solar rays.

12. The Atmosphere and Earth’s Temperature • Gases in the atmosphere surround Earth like a blanket. They keep the temperature in a range that can support life. • The gases keep out some of the sun’s scorching heat during the day. At night, they hold the heat close to the surface, so it doesn’t radiate out into space.

13. The Atmosphere and Earth’s Water • The image to the right shows the role of the atmosphere in the water cycle. • Water vapor rises from Earth’s surface into the atmosphere. As it rises, it cools. • The water vapor may then condense into water droplets and form clouds. • If enough water droplets collect in clouds, they may come together to form larger droplets. These droplets will fall as rain. This is how freshwater gets from the atmosphere back to Earth's surface. The atmosphere is a big part of the water cycle. What do you think would happen to Earth’s water without it?

14. The Atmosphere and Sound • Sound is a form of energy that travels in waves. Sound waves cannot travel through empty space, but they can travel through gases. • Gases in the air allow us to hear most of the sounds in our world. • Because of air, you can hear birds singing, horns tooting, and friends laughing. Without the atmosphere, the world would be a silent, eerie place.

15. In Summary… • The atmosphere is made of gases that are essential for photosynthesis and other life activities. • The atmosphere is a crucial part of the water cycle. It is an important reservoir for water, and the source of precipitation. • The atmosphere moderates Earth's temperature. Weather takes place in the atmosphere. • Without air, Earth would be silent. https://www.youtube.com/watch?v=J5ViCNJAkHg