Chapter 12 Lesson 2 Period 2, 6, & 7

Chapter 12 Lesson 1 Reteach Weather: The condition of Earth’s atmosphere at a particular time and place. Earth’s atmosphere is the envelop of gases that surrounds the planet. Air Pressure: the result of the weight of a column of air pushing down on an area. The atmosphere is heavy The weight of the column of air above your desk is about the same as the weight of a large school bus.

Chapter 12 Lesson 1 Reteach Important of the Atmosphere 1.Makes conditions on Earth suitable for living things. 2.Living things affect atmosphere 3.Constantly changing 4.Living things need warmth and liquid water.

Chapter 12 Lesson 1 Reteach Altitude and the Properties of Air Air pressure decrease as altitude increases. “Altitude or elevation” Air pressure is greater at sea level

Humidity Water enters the atmosphere as part of the water cycle. Amount of water depends on air temperature Warm air = more water than cool air

Clouds Form when air rises and cools Classified according to their shape and their height above Earth’s surface Cirrus, cumulus, and stratus – Others are modified or combinations

How Precipitation Forms Precipitation is all the forms of moisture that fall from the atmosphere to Earth’s surface. Clouds need to have a lot of moisture before it can produce precipitation. Precipitation forms when the drops or crystals become large enough to fall.

Rain & Snow Rain= Water droplets fall from clouds (above freezing) – Temperature directly beneath the cloud is above freezing. Snow = temperature below cloud is below freezing – Falling ice crystals combine to form snowflakes

Sleet & Hail Sleet forms when rain falls through a layer of freezing air that is large enough to freeze the rain. Hail is precipitation that occurs in the form of hard, round particles of ice. – Warmer summer months Hailstones can become as large as baseballs.