Our Atmosphere Chapter 22 Section 1

Warm-up Explain to one another why the layers of the atmosphere are similar to an Oreo cookie

Layers of the Atmosphere

Layers of the Atmosphere There are five layers of the atmosphere Troposphere Stratosphere Mesosphere Thermosphere Ionosphere

Troposphere Densest of all the atmospheric layers Weather occurs here Important: The temperature drops at a constant rate as altitude increases

Temperature Inversion The atmospheric condition in which warm air traps cooler air near the Earth’s surface Traps pollutants in the air causing a haze to form over certain areas

Stratosphere Above the troposphere. Gets warmer with increasing altitude Contains no clouds and no storms Upper part of Stratosphere is the ozone layer

Ozone Layer Ozone is made of three oxygens Absorbs solar radiation

Mesosphere Coldest layer of the atmosphere After the stratosphere

Thermosphere Upper layer of the atmosphere. Gases are very far apart. How do you think this will impact the temperature? Very hot due to the intense solar radiation

Ionosphere Ionosphere reflects radio waves. Where auroras take place.

Changes in the Earth’s Atmosphere Lets talk about photosynthesis. What is the plant taking in? What is the plant giving off?

Man-Made Chemicals The ozone layer is slowly becoming depleted due to the presence of man made chemicals. In the 1930’s a chemical was introduced to refrigerators and aerosol cans called Chlorofluorocarbons or CFC’s. The CFC’s would cause the ozone to split apart leaving only the chlorine behind.

CFC’s The US government banned the use of CFC’s in 1996. Though they are still in use by some countries today. The damage that humans caused is still affecting us today.

Greenhouse Effect The warming of the surface and the lower atmosphere of Earth that occurs when carbon dioxide water vapor and other gases in the air absorb and radiate infrared radiation The greenhouse effect is NOT a bad thing. If we did not have it it would be significantly colder than it is now Greenhouse effect is responsible for keeping us warm!

Global Warming Caused by an increase of carbon dioxide in the atmosphere. Global warming has already caused the polar ice caps to start to melt.

Global Warming cont.

Global Warming Melting of icecaps causes the global sea level to rise. Small islands are now being threatened by the rise in sea level This rise in sea level is also killing off many of the worlds coral reefs.

Water and Wind Section 2

Water Cycle

Water Cycle First step- Evaporation Water is heated and turned into vapor

Water Cycle Second step- Condensation Water vapor begins to cool causing clouds to form

Water Cycle Step three- Precipitation Any form of water that falls to the Earth’s surface from the clouds

Humidity The amount of water vapor in the air We feel most of the humidity in summer. Why? Relative humidity- the actual quantity of water vapor present in the air compared with the maximum quantity that can be present at that particular temperature

Dew Point The temperature at which air begins to condense to a liquid. Higher the humidity higher the dew point

Clouds Are formed when warm air rises and water vapor condenses into tiny water droplets Depending on where they form they can have different shapes and characteristics

Cirrus Thin wispy clouds Occur at high altitudes

Stratus Sheet-like layered clouds Form at lower altitudes

Cumulus White and fluffy clouds with flat base Form at various altitudes

Cloud Names Clouds are often described using a combination of names. Cirrostratus- high layered clouds Altostratus- looks like a veil of clouds with the sun peeking through it Cumulonimbus-precipitation clouds

Air Pressure The pressure due to the weight of the atmosphere Instrument used to measure pressure is the barometer Measured in millimeters of mercury

Wind Differences in pressure create wind Determined by the difference in the pressure gradient. Pressure gradient- place where air pressure varies from one place to another Wind goes from high pressure to low pressure

Coriolis force Responsible for creating winds and weather patterns Everything in the Northern Hemisphere travels to the east (right) due to the Coriolis force.

Global Wind Patterns The Coriolis force plays a big role in how the Earth distributes the weather. As the Earth rotates the wind lags behind causing different latitudes to experience different kinds of weather The United States sits at 30°N latitude and our winds are called the Westerlies.

Global Wind Patterns

Weather and Climate Section 3

Fronts The boundary between air masses of different densities and usually different temperatures Three types: warm cold and stationary

Warm Front Occurs when a mass of warm air moves toward and over a slower mass of cold air The air mass cools forming cirrus and cirrostratus clouds Warm front associated with: precipitation

Warm Front cont.

Cold Front Occurs when cold air is forced on top of warm air and rises quickly Forms cumulonimbus clouds Causes high winds, thunderstorms, and even tornadoes

Cold Front cont.

Stationary Front Occurs when two fronts meet but never actually move on top of one another Movement occurs from side to side Similar weather to warm front

Climate The average weather conditions in an area over a long period of time Is it warmer by the North Pole or the equator? The climate by the equator is more tropical than the North Pole because it gets more direct sunlight

Climate cont. Why is it wet on one side of a mountain and dry on another? Topography plays a role in determining an areas climate The more rough the terrain the more diverse the climate

Seasons Name the four seasons we experience on Earth. Tell me why when the Northern Hemisphere has summer that the Southern Hemisphere has winter

Seasons cont. Occur due to the tilt and rotation of the Earth. Earth’s tilt is 23.5° Fall and Spring Equinox Summer &Winter Solsitce

Symbols of a Weather Map Scientists study weather maps everyday and must learn to read a variety of symbols in order to understand what is going on that day. H and L represent areas of high and low pressure A circle with a arrow pointing of the end represents the cloud cover, temperature and pressure

Symbols cont.

Urban Temperature vs. Suburban Temperatures In urban areas such as Philadelphia the temperature difference is 0.75°C higher than in suburban areas. Why is that? What can we do about it?