Ch 17.1 Atmosphere and Characteristics

How does weather differ from climate?

Weather is constantly changing and refers to the state of the atmosphere at any given place and time

Climate is based on long term weather observations and help describe a region or place.

2.  Describe the composition of the atmosphere including majot components and variable components

** Air is not actually a specific gas or element but instead  is a “mixture” of gases

99 % of clean, dry air is composed of nitrogen and oxygen

Major components:

• Nitrogen
• Oxygen
• Argon 0.93 %
• Carbon dioxide 0.039 %

Variable components vary from time to time and place to place.  They include water vapor, dust particles, and ozone.

Water vapor is the source of all clouds and precipitation.  It absorbs the most solar radiation.

What are the four vertical layers into which the atmosphere can be divided by temperature?

• Thermosphere contains only a fraction of the atmosphere’s mass.  Temp increases b/c oxygen and nitrogen absorb high-energy solar radiatipon
• Mesosphere temperature decreases w/ altitude
• Stratosphere ozone is located here.  The ozone collects UV light which heats the stratosphere
  
• Troposphere weather occurs here temperature decreases w/ altitude

The atmosphere “thins” as you travel away from Earth until there are too few gas molecules to detect.  This causes a decrease in air pressure as altitude increases.

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Why do seasonal changes occur?

The Earth has two principle motions

• rotation is the spinning around on its axis
• revolution is the movement of the Earth around the sun

Seasonal changes occur b/c the Earth’s position relative to the sun  continually changes as it travels around its orbit.