Chapter 1-The Atmosphere 1/29/13

Section 1- The Air around You Weather – the condition of Earth’s atmosphere at a particular time and place. Atmosphere – the layer of gases that surrounds the planet. - The Earth’s atmosphere makes conditions on Earth suitable for living things.

What is the atmosphere made of? Earth’s atmosphere is made up of: Nitrogen Oxygen Carbon dioxide Water vapor Other gases Particles of liquids and solids

Gases in the Atmosphere

Nitrogen Nitrogen is essential for all living things. Most living things cannot take nitrogen, the gas, directly from the air. It needs to be converted by plants to nitrates then to proteins.

Oxygen Oxygen is also needed by living things. Animals can take this gas directly from the air and plants release it as waste. All fuels use oxygen to burn. Ex. Cars, candles, campfire, etc.

Carbon Dioxide Carbon dioxide is essential for plants. Plants need carbon dioxide to produce food. Animals need oxygen to live. Thus each gives off the opposite as waste.

Carbon Dioxide Fuels like coal and gasoline give off CO2. Rising CO2 levels in the atmosphere rises the temperature of the Earth.

Everything else Water vapor is H2O in the form of a gas. The amount of water vapor varies from place to place and time to time. Particles in the atmosphere might be: Dust Smoke Salt

Section 3- Air Pressure Since air has mass, it also has other properties like density and pressure. Density = Mass volume If a substance is more dense, then it has more molecules per unit of volume. So it exerts more pressure.

Pressure Pressure – the force pushing on an area or surface. Air pressure – the result of the weight of a column of air pushing down on an area.

Mass, Volume,and Density Cause Effect If mass and volume then density increases stays the same a. b. stays the same, decreases decreases, c. d.

Measuring Air Pressure Barometer – is an instrument that is used to measure changes in the air pressure. There are two kinds of barometers: Mercury Aneroid

Mercury Barometers A mercury barometer consists of a glass tube open at the bottom end and partially filled with mercury. The space at the top has no air, it’s a vacuum. The bottom end is placed in a bowl of mercury.

Aneroid Barometers Aneroid barometer – has an air tight metal chamber. The metal chamber is sensitive to changes in air pressure. When air pressure increases the walls of the chamber are pushed in. When it decreases, they bulge out. These barometers are smaller and do not contain any liquid.

The Units Most weather reports for the general public use inches of mercury. However, the national weather service uses milibars. -One inch is equal to 33.87 milibars

Increasing Altitude Altitude, or elevation, is the distance above sea level. The higher the altitude, the lower the density. Sea-level altitude has the weight of the whole atmosphere on it. The higher the altitude, the percentage of oxygen goes down.

Increasing Altitude

Section 4- Layers of the atmosphere There are 4 main layers of the atmosphere: Troposphere Stratosphere Mesosphere Thermosphere They are classified according to changes in temperature.

Troposphere Tropo – turning or changing. 0-16 km above the equator. The troposphere is where the Earth’s weather occurs. It is the shallowest layer of the atmosphere. Contains almost all of the mass of the atmosphere. As the altitude increases, temperature decreases.

Stratosphere Strato – layer or spreading out. 16-50km above the equator. The lower part is about -60oC while the upper part is warmer because this is the lower part of the ozone, the 3-atom form of oxygen. The ozone layer absorbs energy from the sun.

Mesosphere Meso – middle This layer is the coldest, -90oC. 50-80km above the earth. This layer is the coldest, -90oC. It protects the Earth from most meteoroids, what you see is a trail of hot, glowing gases.

Thermosphere Thermo – heat 80+km (no definite outer limit) The air is very thin, about .001% than that of sea level. Temperatures reach 1,800oC yet a thermometer will show below 0oC. Why? Molecules are spread out and don’t collide even though they are moving rapidly.

Thermosphere The thermosphere has two parts: Ionosphere - 80-550km where the aurora borealis (Northern Lights) takes place. Exosphere – 550 + km where phone and TV signals bounce off satellites.