Chapter 15 The Atmosphere Mr. Manskopf Notes Also At

Why Care About The Air?

You breathe out of which layer?

The air we breathe and all the weather we see is contained in the lowest 1% of the Earth’s atmosphere. The air we breathe and all the weather we see is contained in the lowest 1% of the Earth’s atmosphere.

Take a deep breath

What is air made out of?

Is air strong? Is it matter?

Why is our atmosphere important? Why doesn’t it float away

Chapter 15 Big Idea Our atmosphere is critical to all life on Earth. Human actions have a great impact on our atmosphere.

Section: Earth’s Atmosphere Describe the properties of the atmosphere. Describe the properties of the atmosphere. Identify the main layers of the atmosphere. Identify the main layers of the atmosphere. Explain how heat is transferred in the atmosphere Explain how heat is transferred in the atmosphere

What is the Atmosphere? Thin layer of gases surrounding our planet Skin of apple thin Skin of apple thin We live at bottom We live at bottom Air is a fluid Air is a fluid Why don’t gases fly away into space? Why don’t gases fly away into space?

Why is it important? Earth’s atmosphere makes life on Earth possible. Protects us from sun’s rays. Protects us from sun’s rays. Provides vital gases like oxygen, nitrogen and carbon dioxide. Provides vital gases like oxygen, nitrogen and carbon dioxide. Keeps temperature comfortable Keeps temperature comfortable Allows water to circulate around planet. Allows water to circulate around planet. Protects us from meteoroids. Protects us from meteoroids.

The Air Around You Weather Weather is the state of the atmosphere at any one moment.

What is it made of? Earth’s Atmosphere is made of: 78 % Nitrogen 78 % Nitrogen 21% Oxygen 21% Oxygen 1% a bunch of others (Argon, Carbon Dioxide, Water Vapor…) 1% a bunch of others (Argon, Carbon Dioxide, Water Vapor…)

Carbon Dioxide vs Carbon Monoxide?

Water in the Air Relative Humidity Amount of water vapor in the air Changes constantly Warm Air = More Moisture Condensation = Clouds

Cloud Formation

Air temperature Changes vertically and horizontally on Earth Why is it cold on top of mountains? Why is it cold on top of mountains? Why are the tropics warmer than the polar regions? Why are the tropics warmer than the polar regions?

Air Pressure The force of a column of air pushing down on an area Where is air pressure greater, sea level or top of a mountain? Why are airplanes pressurized?

As altitude increases air pressure decreases…quickly

Barometers An instrument used to measure air pressure.

Changing air pressure is a great indicator of weather changes.

Air pressure Differences in air pressure is going to help us understand: Wind Wind Cloud formation Cloud formation Tornadoes Tornadoes Almost all weather Almost all weather

Four Main Layers of Atmosphere The four main layers of our atmosphere are classified according to changes in temperature. Troposphere Troposphere Stratosphere Stratosphere Mesosphere Mesosphere Thermosphere Thermosphere

The Troposphere The Troposphere: Inner most layer Inner most layer (0 to 12km) Where all weather occurs Where all weather occurs The temperature decreases to -60 degrees at top. The temperature decreases to -60 degrees at top.

The Troposphere Clouds, rain, snow and all precipitation occur here. Air Pressure and Temperature drop quickly in troposphere.

Stratosphere Layer above troposphere where atmosphere warms slightly Ozone layer located there blocks out harmful UV Rays

Mesosphere “Middle Layer” “Middle Layer” Temperatures reach - 90 degrees Celsius Temperatures reach - 90 degrees Celsius Where meteoroids burn up in atmosphere Where meteoroids burn up in atmosphere

Thermosphere “Thermo” means heat “Thermo” means heat Air is only % as dense as sea level Air is only % as dense as sea level Air slowly blends into outer space Air slowly blends into outer space Hottest layer of atmosphere because energy from the sun strikes it first Hottest layer of atmosphere because energy from the sun strikes it first

Heat Transfer in the Troposphere 1) Radiation: The transfer of energy through space, such as heat from the sun to Earth’s atmosphere

2) Conduction: The transfer of heat directly between two objects that are in contact

3) Convection: The transfer of heat by the movement of currents within a fluid (liquid or gas)

Air Masses And Fronts The Air Outside Today, Was Somewhere Else Yesterday

What IS An Air Mass? An Air Mass is a huge body of air with similar temperature, humidity and pressure. They sometimes spread over hundreds of square miles.

Types of Air Masses There are 4 main types of air masses: 1) Polar 2) Tropical 3) Maritime 4) Continental Each has unique weather associated with it.

4 Major Air Masses of North America Maritime Tropical: Warm, Moist Air Maritime Tropical: Warm, Moist Air Maritime Polar: Cold, Moist Air Maritime Polar: Cold, Moist Air Continental Tropical: Warm, Dry Air Continental Tropical: Warm, Dry Air Continental Polar: Cold, Dry Air Continental Polar: Cold, Dry Air Where do each of these air masses originate?

Temperature dropped 20 degrees between 6AM and 11AM. WHY?

Part 2 Air Masses and Fronts What type of air mass yesterday vs. today?

What Are Fronts? Fronts are areas where 2 or more air masses collide. Air with different temperature, humidity and pressure DO NOT MIX WELL.

Types of Fronts There are four types of front: 1) Cold Front 2) Warm Front 3) Stationary Front 4) Occluded Front

Cold Fronts Cold Fronts occur where cold air runs into slowly moving warm air. Cold air being more dense pushes warm air up. Warm moist rising air can cause clouds and storms.

Cold Fronts Cold Fronts: Often move quickly Often move quickly Can bring abrupt changes to weather (summer storms) Can bring abrupt changes to weather (summer storms) Behind front is often cool and clear weather Behind front is often cool and clear weather

Cold Fronts

Warm Fronts Warm Fronts occur where a warm air mass collides with a slower moving cold air mass. Because warm air is less dense, it rides above the cold air.

Warm Fronts Warm Fronts move more slowly than cold fronts so weather changes occur more slowly. In winter they often bring snow.

Warm Fronts