Science Test Study Guide Unit: Weather 1. Describe why winds at the ocean change direction between day and night. During the day at the ocean, there is a sea breeze. The land heats up much quicker than the water, so there is a lot of warm air rising and the cold air from the ocean (water takes a lot longer than land to heat up) is rushing in to take its place (Remember: Wind is created when warm air rises and cold air rushes in to takes its place). During the night at the ocean, there is a land breeze. The water cools down much slower than the land, so the warm air is now rising from the ocean and the cold air from the land (land cools down much faster than water) is rushing in to take its place. 2. Which direction do air masses and weather systems move across the USA and what global wind is responsible for their movement? Air masses and weather systems move across the USA from west to east. Prevailing Westerlies are responsible for their movement. 3. How can the jet stream be described? The jet stream is a global river of wind high up in the atmosphere. It is the dividing line between warm air and cold air across the United States. As the jet streams shifts, temperatures and weather across the United States shift; as the jet stream sinks further south, it brings cold air with it; as the jet stream moves further north, it bring warm air with it. 4. Explain the difference between El Nino and La Nina and how those patterns affect the East Coast of the USA, including NC. A global El Nino pattern is when the ocean waters around the equator are warm and a global La Nina pattern is when the ocean waters around the equator are cold. During an El Nino pattern, the jet stream is pushed south; this means cooler temperatures and increased precipitation for the East coast of the USA. The west coast of the USA will be very wet. The Atlantic hurricane season is also less active. During a La Nina pattern, the jet stream is pushed north; this means warmer temperatures and decreased precipitation for the East coast of the USA. The Atlantic hurricane season is also more active. 5. Describe the Gulf Stream and explain how it affects weather patterns The Gulf Stream is a warm ocean current off the East Coast of USA. It affects weather patterns by helping to keep the weather along the East Coast mild by warming the air and land there during the cooler months. It also helps keep winters general mild along the western coast of Europe. 6. How does location near a body of water make local temperatures milder? Water takes a longer time to cool off than land, so the air above a body of water has warmer temperatures, which then affects the temperatures of surrounding areas. 7. What conditions are needed for a hurricane to form off the coast of North Carolina? You need warm water temperatures and a tropical storm moving from the southeast.