1. Low pressure systems can bring violent weather.
S of I—Patterns of movement within systems result in interaction and change.

2. Warm Up # 32 Copy and answer.
1. Explain why hurricanes
are caused by Low
Pressure Systems.
2. Name and describe each of the three types of clouds.
3. What type of weather is associated with a high pressure system?

3. Vocab to remember
tropical storm--a low pressure system near the equator with winds at least 40 mph
hurricane--a tropical low pressure system with winds at least 74 mph
storm surge--a huge mass of ocean water pushed by a hurricane into a coastal area
blizzard--blinding snowstorm with winds at least 35 mph and temperatures usually below 20* F

4. Hurricanes
Warm ocean water near the equator can turn a low pressure center into a violent storm.
More and more energy is added as more warm water evaporates and becomes part of the system.
The Coriolis Effect causes the system to move in a spiral.
The system becomes a tropical storm when winds reach at least 40 mph.
It becomes a hurricane when the winds reach 74 mph.

5. Why do hurricanes usually form between Aug and Oct in the US?

6. How hurricanes develop
Tropical storms usually move westward due to trade winds. As long as it stays over warm water, it gains energy and becomes more powerful.
As soon as it moves over cooler water or hits land it loses energy and begins to die out.
As the hurricane moves, a small area of clear weather moves through as the center passes over.
This is called the eye of the storm.

7. When a hurricane hits Hurricanes pound the coast with huge waves,
strong winds, and heavy rains.
Tornadoes can be produced.
Floods and storm surges can happen.
The National Hurricane Center can track progress
of a storm and can warn if evacuation is necessary.

8. Winter storms Winter storms form as part of low pressure systems.
They form when two air masses collide.
When a continental polar air mass and a maritime polar air mass come together winter storms can happen.

9. Three types of winter storms
Blizzards--strong winds and very cold temperatures
Northern and Central states
Lake effect snows--form east and south of the
Great Lakes
Ice storms--freezing rain covers the ground, limbs,
and power lines with ice

12. Exit Ticket
Use your scientific knowledge of pressure systems to answer one of the following questions:
FQ—What is the relationship between air pressure and weather?
CQ—How can pressure cause positive and negative change?