High School

Earth Science

Week 4: April 27- May 1

Essential Vocabulary

• Weather: The state of the atmosphere at any given time.

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• Climate: The sum of all weather information that helps to describe a place or region.

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• Elements (of weather and climate): Quantities or properties of the atmosphere that are measured regularly and that are used to express the nature of weather or climate.

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Essential Vocabulary

• Air: The mixture of many discrete gases, in which varying quantities of tiny solid and liquid particles are suspended.

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• Aerosols: The tiny solid and liquid particles suspended in the atmosphere.

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• Ozone: A molecule of oxygen that contains 3 oxygen atoms.

Essential Vocabulary

• Troposphere: The lowermost layer of the atmosphere. Temperature decreases with height.

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• Environmental lapse rate: The rate of temperature decreases with increasing height in the troposphere.

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• Radiosonde: A lightweight package of weather instruments fitted with a radio transmitter and carried aloft by a balloon.

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• Stratosphere: The layer of atmosphere immediately above the troposphere. Temperatures increase with height due to ozone layer.

Essential Vocabulary

• Mesosphere: The layer of atmosphere immediately above the stratosphere. Temperatures decrease with height. Coldest layer of atmosphere.

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• Thermosphere: The layer of atmosphere immediately above the mesosphere. Temperatures increase with height due to absorption of short wave solar radiation.

Focus On The Atmosphere

• Weather is what is going on in the atmosphere over a short period of time. Weather is constantly changing.

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• Climate is atmospheric conditions over a long period of time -- �the “average weather” of an area, or a generalized composite of the weather.

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• Elements of weather and climate are properties that are measured regularly. The most important of these include temperature, humidity, cloudiness, precipitation, air pressure and wind speed and direction.

Composition Of The Atmosphere

Air is a mixture of discrete gases. The major components of clean, dry air are:

• Nitrogen (N) 78%,
• Oxygen (O) 21%
• Carbon Dioxide (CO₂) .04% Carbon dioxide absorbs heat energy. It is a greenhouse gas.
• Argon and other gases.

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Composition Of The Atmosphere

There are variable components of our atmosphere. These include:

• Water vapor: Up to 4% of the air’s volume. Water vapor for clouds and precipitation. Water vapor also absorbs heat energy.
• Aerosols: These are tiny particles dispersed in the air. Water vapor can condense on these sold particles. When water vapor condenses on these particles, they are called condensation nuclei. These particles also can reflect sunlight. They help color the sunset.
• Ozone: Ozone is three atoms of oxygen (O₃). Ozone is found between 10 and 50 km above the surface of Earth and its distribution is not uniform. Ozone absorbs harmful UV radiation. Human activity is depleting ozone by adding CFCs (chlorofluorocarbons) to the air.

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Vertical Structure Of The Atmosphere

• Air pressure is the weight of the air above. Average seal level air pressure is slightly more than 1000 millibars. This is about 14.7 pounds of pressure per square inch.

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• Air pressure decreases with altitude. One half of the atmosphere is found below 3.5 miles (5.6 kilometers). Ninety percent of the atmosphere is found below 10 miles (16 kilometers).

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Vertical Structure Of The Atmosphere

The layers of the atmosphere are divided according to how the temperature changes with altitude:

• Troposphere: The troposphere is the bottom layer. It is known as the “weather sphere” because our weather happens in the troposphere. Temperatures in the troposphere decrease with altitude. This means that it gets colder as you go higher. Temperature decrease with altitude is called environmental lapse rate. In the troposphere, the environmental lapse rate averages 6.5º C per kilometer or 3.5º F per 100 feet. The thickness of the troposphere varies with latitude and season. It has an average height of 12 kilometers. The boundary between the troposphere and the next layer (stratosphere) is the tropopause.

Vertical Structure Of The Atmosphere

• Stratosphere: The stratosphere is the second layer of the atmosphere. Temperatures in the stratosphere stay constant to a height of about 20 km and then increase with height. This means that it gets warmer as you go higher. The stratosphere is between 12 km to 50 kilometers above the ground. The stratosphere contains the ozone layer. The boundary between the stratosphere and the next layer (mesosphere) is the stratopause.

Vertical Structure Of The Atmosphere

• Mesosphere: The mesosphere is the third layer of the atmosphere. Temperatures in the mesosphere decrease with height. The mesosphere is the coldest layer of our atmosphere. It is also one of the least explored regions of the atmosphere. It is between 50 km and 80 kilometers above the ground. The boundary between the mesosphere and the next layer (thermosphere) is the mesopause.

Vertical Structure Of The Atmosphere

• Thermosphere: The thermosphere is the fourth layer of the atmosphere. It contains only a fraction of the atmosphere’s mass. Temperatures in the thermosphere increase with height due to the absorption of solar radiation by atoms of oxygen and nitrogen. The high temperature in the thermosphere is due to the gases moving at high speeds. Because the gases are so spread out, the gases possess only an insignificant quantity of heat. If you put your hand in the thermosphere, it would not feel hot. The thermosphere does not have a well-defined upper limit. We call the area above the thermosphere the exosphere -- the place where atmosphere is escaping into space. Auroras occur in the thermosphere.

Riddle

What did one raindrop say to the other?

Answer

Two’s company, three’s a cloud!