Weather Changes As Air Masses Move 3.1/3.2

VOCABULARY Air Mass: A large volume of air that has nearly the same temperature and humidity at different locations at the same altitude. Front: The boundary between air masses. High-Pressure System: A generally calm and clear weather system that occurs when air sinks down in a high-pressure center and spreads out toward areas of lower pressure as it nears the ground. Low-Pressure System: A large often stormy weather system that occurs when air moves around and into a low-pressure center then moves up to higher altitudes. Tropical Storm: A low-pressure system that starts in the tropics with wind of at least 65 KM per hour but less than 120 KM per hour. Hurricane: A tropical low-pressure system with sustained winds of 120 KM per hour. Storm Surge: A rapid rise in water level in a coastal area that occurs when a hurricane pushes a huge mass of ocean water. Blizzard: A blinding snowstorm with winds of at least 56 KM per hour.

Air Masses are Large Bodies Weather changes when new air mass moves into your area. Air mass is a large volume of air in which temperature and humidity are nearly the same altitude.

Characteristics of an Air Mass Continental air masses form over land. Air becomes dry as it loses the moisture to the dry land below it. Maritime air masses form over water. Air becomes moisture as it gains water vapor from the water below it.

Characteristics of an Air Mass Tropical air masses form near the equator. Air becomes warm as it gains energy from the warm land or water. Polar air masses form far from the equator. Air becomes cool as it loses energy to the cold land or water.

Cold Front

Warm Front

Stationary Front

Formation of Hurricanes In the eastern United States, hurricanes most often strike between August and October. Energy from water is necessary for low-pressure center to build into a tropical and then into a low-pressure center to build a tropical storm into then into a hurricane.

Effects of Hurricanes Hurricanes can pound a coast with huge waves and sweep the land with strong winds and heavy rains. The storms cause damage and dangerous conditions in several ways.

Blizzards Strong winds that can blow so much snow into the air at once that it becomes difficult to see and dangerous to travel

Fun Facts ! The word hurricane comes from the Taino Native American word, hurucane, meaning evil spirit of the wind. Every second, a large hurricane releases the energy of 10 atomic bombs. A typical hurricane can dump 6 inches to a foot of rain across a region. The most violent winds and heaviest rains take place in the eye wall, the ring of clouds and thunderstorms closely surrounding the eye.

VIDEO Here is a short 2:30 video if we have time and the class is quiet we will watch it. http://video.nationalgeographic.com/video/101-videos/hurricanes-101