Weather & Climate The Air Around Us
What is Air? It’s Got Us Covered Air is made up of matter- it takes up space. Air is a mixture of gases- tiny particles in motion. Air is made up of nitrogen, oxygen, carbon dioxide, & water vapor.
Properties of Air Because air has mass, it also has other properties, including density and pressure. Density- the amount of mass in a given volume of air You can calculate density by dividing mass by volume Pressure The force pushing on an area or surface
Air pressure is the result of the weight of a column of air pushing down on an area. The weight of the column of air above your desk is about the same as the weight of a large school bus! molecules in air push in all directions—down, up, and sideways
Measuring Air Pressure barometer is an instrument that is used to measure changes in air pressure There are two kinds of barometers: mercury barometers and aneroid barometers.
Mercury Barometers consists of a glass tube open at the bottom end and partially filled with mercury. Air pressure pushes down on the surface of the mercury in the dish, causing the mercury in the tube to rise.
Aneroid Barometers aneroid means “without liquid.” has an airtight metal chamber Changes in air pressure cause the walls of the airtight metal chamber to flex in and out. The needle on the dial indicates the air pressure.
Earth’s Blanket Of Air Atmosphere- A blanket of air that always surrounds Earth. The atmosphere is made up of 4 layers -Troposphere (it’s where we live) -Stratosphere -Mesosphere -Thermosphere
Sometimes It’s a Wet Blanket Weather- The condition of the atmosphere at a certain place and time. When talking about weather, you are actually describing what is happening in the atmosphere. Weather is constantly changing. Without the atmosphere, there would be no weather!
Not Too Warm, Not Too Cold A Gardener’s Greenhouse… Sun rays enter greenhouse and strike surfaces. Heated air rises Glass traps heat inside.
Earth’s Greenhouse Earth’s atmosphere acts like a greenhouse… Sun passes through the atmosphere and heats land & water. Some heat goes back into the atmosphere. Heat trapped by water vapor, carbon dioxide, & other gases will be sent back to Earth.
Feeling the Air Dark colored materials heat up quicker than light colored materials. So air above dark colored surfaces heats up quicker. When air is warmed the particles spread out. Warm air becomes lighter & rises. The cooler air sinks. This movement of air is called WIND.
Land & Sea Breezes Land Breeze (cool land/warm sea) Cool air over land moves out toward the water and takes the place of rising air. Warm air over the water rises. Sea Breeze (warm land/cool sea) Warm air over the land rises. Cool air over the water moves toward land and takes the place of the warmer air that has risen.