Air

What’s in air?

The atmosphere is made up mostly of nitrogen gas. Oxygen makes up a little more than 20% of the atmosphere. Air Composition

What happens to air as altitude increases? Altitude- distance above sea level. As you increase altitude, air pressure decreases (there is less air above you). As you increase altitude density decrease (there are less air molecules further up, per given space).

Properties of Air Mass- Air has mass (it contains matter, “stuff”) Density- Because air has mass, it has density D = m/v Air produces pressure. Air pushes down on all objects on the Earth. You don’t feel it because it pushes on you in all directions (up, down, sideways).

Water Temperature vs. Land Temperature Land warms (gains heat) much faster than a body of water Land cools (loses heat) much faster than a body of water This uneven heating of Earth’s surface causes wind

Water Temperature Oceans cover more than 2/3 of Earth’s surface, thus it absorbs more sunlight and stores more heat Land Temperature Land is made of many materials which absorb the sun’s rays differently

Local Winds Sea Breeze- Happens during the day. Cool air above the ocean or sea moves towards the warm air above the land. The cool air above the ocean has a higher pressure and the warm air above the land has a lower pressure. Air always move from an area of high pressure to low pressure, creating the wind.

Local Winds Land Breeze- Happens during the night. Cool air from the land moves towards the warm air above the ocean. The cool air above the land has a higher pressure and the warm air above the ocean has a lower pressure. Air always move from an area of high pressure to low pressure, creating the wind.

Global Winds The sun’s rays does not hit the surface of the Earth equally. The Equator receives more direct rays, therefore it is warmer. The poles receive indirect rays, therefore it’s colder. The Poles have colder air and high pressure. The equator has warmer air and low pressure. The air moves from the high pressure area to the low pressure creating global winds. The movement of the winds around the globe is called: GLOBAL CONVECTION CURRENTS

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Cool AirWarm air Type of Pressure High PressureLow Pressure Amount of Density More DenseLess Dense Amount of Water Vapor Less water vapor More water vapor

Sea BreezeLand Breeze Temperature of Air Above the Land WarmCool Temperature of Air Above the Sea CoolWarm Type of Pressure Above the Land Low pressureHigh pressure Type of Pressure Above the Sea High pressureLow pressure Time of Day DayNight

Atmospheric Pressure and Temperature The atmosphere is held around the Earth by gravity. Gravity pulls gas molecules in the atmosphere toward the Earth’s surface, causing air pressure. As altitude increases, air pressure decreases. Air temperature decreases as altitude increases. Lower parts of the atmosphere are warmer because they contain a high percentage of gases that absorb solar energy.

Radiation: Energy Transfer by Waves The Earth receives energy from the sun by radiation. Radiation is the transfer of energy as electromagnetic waves. Conduction: Energy Transfer by Contact Thermal conduction is the transfer of thermal energy through a material. Convection: Energy Transfer by Circulation Convection is the transfer of thermal energy by the circulation or movement of a liquid or gas. Energy in the Atmosphere