Starter 1.Which of these processes of the water cycle Test Taking Tip Evaluating and Revising Frequently, a scientifically accurate answer choice may not answer the question that is being asked. Verify what the question is asking. Determine if an answer choice is a true statement or not. Determine if a true answer choice actually answers the question. Be cautious with inserted or deleted words that make a false statement seem accurate. 1.Which of these processes of the water cycle The stream’s greatest velocity is at its bottom. is a direct effect of the sun’s energy? The stream’s bed load helps erode the stream’s bottom. Formation of precipitation Natural levees restrict the lateral movement of stream water. Runoff of water over soil Evaporation Uplift creates a new base level for the stream. Seeping of water into soil 2. Which factor is most important in determining the erosive power of a stream? 4. When a soil is impermeable, it Allows water to flow freely through it. Stream discharge Has no water in it at all. Dissolved load Does not allow water to pass through it. Stream velocity Channel width Has large pore spaces. 3. Rejuvenation causes streams to resume downcutting their channels because

Objectives page 36 Today, you will be able to: Compare and contrast weather and climate. Explain why seasonal changes occur.

Composition of the Atmosphere Weather is constantly changing, and it refers to the state of the atmosphere at any given time and place. Umbrella or no umbrella? Shorts or long sleeves? Climate, however, is based on observations of weather that have been collected over many years. Climate helps describe a place or region. Determines your wardrobe Average weather

Composition of the Atmosphere Major Components Air is a mixture of different gases and particles, each with its own physical properties. Nitrogen (78%) – Most abundant gas in the atmosphere Oxygen (21%) Carbon dioxide, Argon, Water Vapor (varies) , other trace gases – (1%)

Composition of the Atmosphere 1% 21% 78%

Composition of the Atmosphere Variable Components Water vapor is the source of all clouds and precipitation. water vapor absorbs heat given off by Earth. It also absorbs some solar energy. How do clouds form? Ozone is a form of oxygen that combines three oxygen atoms into each molecule (O3). If ozone did not filter most UV radiation and all of the sun’s UV rays reached the surface of Earth, our planet would be uninhabitable for many living organisms.

Composition of the Atmosphere Human Influence Primary Pollutants – emitted directly from an identifiable source Emissions from transportation vehicles account for nearly half the primary pollutants by weight. Secondary Pollutants – not emitted directly into the air Sulfur dioxide is emitted→combines with oxygen→makes sulfur trioxide→combines with water→irritating and corrosive acid Nitrogen oxides absorb solar radiation→smog can be produced

Primary Pollutants

Height and Structure of the Atmosphere The atmosphere rapidly thins as you travel away from Earth until there are too few gas molecules to detect. Pressure Changes Atmospheric pressure is simply the weight of the air above. The density of the air decreases as your altitude increases.

Atmospheric Pressure vs. Altitude In this picture, you can see that the top of the mountain is colder than the bottom because of the snow. However, not all layers of the atmosphere show this temperature pattern.

Atmosphere Characteristics Temperature Changes • The atmosphere can be divided vertically into four layers based on temperature. The troposphere is the bottom layer of the atmosphere -temperature decreases with an increase in altitude. - This is where ALL weather occurs. - varies with latitude and seasons •

The stratosphere - temperature remains constant, then begins a gradual increase because of the ozone layer. - Ozone layer absorbs ultraviolent radiation (UV)

Snowy Mountaintops Contrast with Warmer Snow-Free Lowlands

Atmosphere Characteristics The mesosphere - immediately above the stratosphere and is characterized by decreasing temperatures with altitude. - Most meteors burn out in this layer - Coldest layer The thermosphere is immediately above the mesosphere and is characterized by increasing temperatures due to the absorption of very short-wave solar energy by oxygen. - Outer layer - Hottest layer - Aurora Borealis (Northern Lights)

Thermal Structure of the Atmosphere

Atmosphere Characteristics Earth-Sun Relationships Earth’s Motions Earth has two principal motions—rotation (movement around axis; 24 hours) and revolution (movement around the sun; 365 days). Earth’s Orientation Seasonal changes occur because Earth’s position relative to the sun continually changes as it travels along its orbit. - Earth is tilted on its axis - Tilted at 23.5º from the perpendicular

Atmosphere Characteristics Earth-Sun Relationships Solstices and Equinoxes The summer solstice is the solstice that occurs on June 21 or 22 in the Northern Hemisphere “official” first day of summer. The winter solstice is the solstice that occurs on December 21 or 22 in the Northern Hemisphere “official” first day of winter.

Atmosphere Characteristics Earth-Sun Relationships The autumnal equinox is the equinox that occurs on September 22 or 23 in the Northern Hemisphere. “official” first day of autumn or fall The spring equinox is the equinox that occurs on March 21 or 22 in the Northern Hemisphere. “official” first day of spring

Solstices and Equinoxes

Atmosphere Characteristics Length of Daylight The length of daylight compared to the length of darkness also is determined by Earth’s position in orbit. - During Summer Solstice in the Northern Hemisphere, daylight is greater than the length of darkness. - The farther you move north of the equator during summer solstice, the longer the length of daylight. - Artic Circle – length of daylight is 24 hours.

Tilt of Earth’s Axis

Atmospheric Layers Foldable (page 35)

Atmospheric Layers Foldable (page 35)

Atmospheric Layers Foldable (page 35)

Atmospheric Layers Foldable (page 35)

Atmospheric Layers Foldable (page 35)

Atmospheric Layers Foldable (page 35)

Post-Test (page 36)