Weather and Climate Chapter 24 -- pg. 744-787

Chapter 24.1 The Atmosphere Key Terms: Atmosphere Air pressure Barometer Troposphere Weather Stratosphere Ozone layer Mesosphere Thermosphere Ionosphere Aurora

24.1 Key Concepts How does the atmosphere affect conditions on Earth? What is Earth’s atmosphere composed of? How do pressure and density vary with altitude? What are the characteristics of the major layers of the atmosphere?

24.1 The Atmosphere The study of the atmosphere is called Meteorology. The study of meteorology also covers the study of weather and climate. Weather is the general condition of the atmosphere at a particular time and place. Climate is the general weather conditions over a period of years.

24.1 The Atmosphere Atmosphere: A layer of gas that surrounds Earth The atmosphere forms a protective boundary between Earth and space and provides conditions that are suitable for life

24.1 The Atmosphere The atmosphere holds in heat and helps regulate temperatures that are suitable for life. The two most prevalent substances in our atmosphere are carbon dioxide and water vapor (both are waste products we exhale).

24.1 The Atmosphere Air Pressure: the force exerted by the weight of a column of air on a surface. This weight is a result of gravity Air pressure changes with altitude. Is most dense near surface and less dense as altitude rises. As altitude increases, air pressure and density decreases

24.1 The Atmosphere Barometer: an instrument used to measure air pressure. As air pressure increases, mercury in the column rises. As air pressure decreases, mercury in the column falls.

24.1 The Atmosphere Layers of The Atmosphere: Troposphere Stratosphere Mesosphere Thermosphere Ionosphere

24.1 The Atmosphere Troposphere: lowest layer Contains almost all atmosphere’s water vapor Most weather takes place here Average height is 12 km

24.1 The Atmosphere Stratosphere: 2nd layer of atmosphere 12-50 km is height Layer in which ozone is present Absorbs UV radiation which is harmful to life Layer in which planes and weather balloons travel

24.1 The Atmosphere Mesosphere: 3rd layer of atmosphere 50-80 km in height At top of mesosphere temps reach -90 Air moves 320 km/hr Meteoroids that enter the atmosphere burn up here

24.1 The Atmosphere Thermosphere: outermost layer of the atmosphere 80-? Km no boundaries marks end of atmosphere

24.1 The Atmosphere Ionosphere: not a distinct layer Region of charged particles, or ions, that overlaps the lower thermosphere Aurora: a colorful display of light in the sky Ions become attracted to magnetic poles of Earth and start to glow. EXAMPLE: Northern Lights

24.2 The Sun and the Seasons Key terms: Rotation Revolution Tropic zone Temperate zones Polar zones Solstice Equinox

24.2 Key Concepts What are two ways in which Earth moves? Who is Earth’s surface divided into zones based on latitude? What causes the seasons?

24.2 The Sun and the Seasons The Earth moves in two different ways Rotation: the spinning of Earth on its axis Causes day and night 24 hours for Earth to make one rotation Revolution: the movement of one body around another Earth revolves around the sun Takes 365.25 days for Earth to make one revolution

24.2 The Sun and the Seasons Latitude Zones: three regions within which the temperatures are generally the same Tropic zone Temperate zone Polar zone

24.2 The Sun and the Seasons Seasons: caused by the tilt of Earth’s axis as it moves around the sun 23.5 degree tilt Summer Fall Winter Spring

24.2 The Sun and the Seasons Solstices: occurs on the two days a year when the sun is directly overhead Northern hemisphere: Summer solstice  June 21st Longest day of the year Winter solstice  December 21st Shortest day of the year

24.2 The Sun and the Seasons Equinox: neither hemisphere is tilted towards the sun, the length of both day and night are approximately equal. Northern Hemisphere Vernal equinox  March 21st Autumnal equinox  September 21st

24.3 Solar Energy and Winds Key terms: Greenhouse effect Wind Local wind Sea breeze Land breeze Global winds Coriolis effect Monsoon Jet stream

24.3 Key Concepts What happens to the energy the Earth receives from the sun? How is energy transferred within the troposphere? What causes winds? What are some examples of local winds and global winds?

24.3 The Sun and the Seasons Some solar energy that reaches Earth’s atmosphere is reflected back, some is absorbed by the atmosphere, and some is absorbed by Earth’s surface. 50% absorbed by surface 25% reflected by clouds, dust, and gases 20% absorbed by clouds and gases 5% reflected by surface

24.3 The Sun and the Seasons Greenhouse effect: Gases in the atmosphere releases absorbed energy to the Earth’s surface Energy is transferred in three ways: Radiation Conduction Convection

24.3 The Sun and the Seasons Wind: horizontal movement of air Caused by differences in air pressure Caused by unequal heating of Earth’s surface Naturally flows from areas of high pressure to areas of low pressure. As air is heated it expands and becomes less dense and rises. Cool air flows to replace it thus creating wind.

24.3 The Sun and the Seasons Local Winds: The breezes that occur where land meets a large body of water are examples of local winds. Water has a higher specific heat than land. The sun heats and cools the land quicker than the water. The air above the land heats quicker than the air above the water During the day: The warmer air above the water will expand and rise, creating a low pressure area above the water. The cooler air above the land flows to replace it. During the night:

24.3 The Sun and the Seasons Sea Breeze: The cooler air over the water flows towards land Occurs during the day time Land Breeze: The cooler over land flows towards the water Occurs during the night time

24.3 The Sun and the Seasons Global winds: Winds that blow over long distances from a specific direction

24.3 The Sun and the Seasons Convection Cells: global winds move in a series of huge bands If Earth wasn’t rotating on its axis winds would flow in straight lines.

24.3 The Sun and the Seasons Coriolis Effect: the curving effect the Earth’s rotation has on all free-moving objects. If the United States shoots a rocket towards the north pole it will travel exactly in a straight line. It’s the Earth’s rotation underneath the rocket that gives it the illusion of curving.

24.3 The Sun and the Seasons Monsoon: a wind system that is characterized by seasonal reversal of direction Extreme land and sea breeze Summer monsoon: Brings cool temperatures and heavy rain Winter monsoon: Brings very hot and dry weather

24.3 The Sun and the Seasons Jet stream: a belt of high-speed wind in the upper troposphere Develop at high altitudes by great differences in air pressure.

24.4 Water in the Atmosphere Humidity: the amount of water vapor in the air. Relative Humidity: is expressed in %. 40% humidity means the air contains 40% water vapor.

24.4 Water in the Atmosphere Clouds form as warm, moist air rises and water vapor condenses in the atmosphere. Types of clouds: Stratus Cumulus Cirrus

24.4 Water in the Atmosphere Stratus: flat layers of clouds that cover much or all of the sky. Meaning: “Spread out” When Nimbo or Nimbus is added to cloud’s name, it means that the cloud produces precipitation. EXAMPLE: Nimbostratus

24.4 Water in the Atmosphere Cumulus: puffy white clouds that look like piles of cotton balls with flat bottoms. Meaning: “Heap”

24.4 Water in the Atmosphere Cirrus: Thin, white, wispy clouds, often with a feathery or veil-like appearance. Often blow into an area ahead of rain-producing clouds.

24.4 Water in the Atmosphere Forms of precipitation: Rain Snow Hail Sleet Freezing Rain

24.5 Weather Patterns Air Mass: forms when a large body of air becomes fairly stationary over a region of Earth’s surface or as air moves over a large, uniform region like an ocean.

24.5 Weather Patterns Fronts: a defined boundary that forms when two unlike air masses meet. 4 types of fronts: Cold Warm Stationary Occluded

24.5 Weather Patterns Cold front: occurs when a cold air mass overtakes a warm air mass. Cumulus or cumulonimbus clouds are often produced. Causing severe wind and thunderstorms

24.5 Weather Patterns Warm fronts: occurs when a warm air mass overtakes a cold air mass. Usually produces stratus or nimbostratus clouds and a heavy steady rain.

24.5 Weather Patterns Stationary front: two unlike air masses have formed a boundary but neither is moving.

24.5 Weather Patterns Occluded front: occurs when a warm air mass is caught between two cold air masses A rare front that forces the warm air mass up, cutting it off from the ground and trapping it between two cold air masses. Causes cloudy days and some precipitation.