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weather 2
weather test second set
Term | Definition |
---|---|
What is precipitaton? | Any form of water that falls from clouds and reaches Earth’s surface. |
What are the common types of precipitation? | Rain, sleet, freezing rain, snow, hail |
What is rain? | Drops of water at least 0.5mm in diameter |
What is drizzle? | Drops of water that are less than 0.5mm |
What is mist? | Drops of water even smaller than drizzle |
What is a rain gauge? | An open-ended tube that collects rain. |
What is freezing rain? | Rain drops that fall as liquid water but freeze when they touch a cold surface. |
What is snow? | water vapor in a cloud that is converted directly into ice crystals. |
What is hail? | A round pellet of ice larger than 5mm in diameter. Only form inside cumulonimbus clouds. |
What is sleet? | Ice particles smaller than 5mm in diameter. |
What is a flood? | An overflowing of water in a normally dry area. |
What is a drought? | A long period of scarce rainfall or dry weather. |
What causes droughts? | Dry weather systems that remain in one place for weeks or months at a time. |
What is an air mass? | A huge body of air in the lower atmosphere that has similar temperature, humidity, and air pressure at any given height. |
How do scientists classify air masses? | According to temperature and humidity |
What are the types of air masses? | Maritime tropical, continental tropical, maritime polar, continental polar |
What is a tropical air mass? | Warm air masses form in the tropics and have a low air pressure. |
What is a polar air mass? | Cold air masses form north of 50 degrees north latitude and south of 50 degrees south latitude. They have high air pressure. |
What is a maritime air mass? | Form over oceans. Water evaporates from the oceans so the air becomes very humid. |
What is a continental air mass? | Air masses that form over land. They have less exposure to large amounts of moisture from bodies of water. They are drier than maritime air masses. |
What is a martime polar air mass? | Cool, humid air masses that form over the icy cold North Atlantic ocean |
What is a continental polar air mass? | Large air masses that form over Canada and Alaska and can bring bitterly cold weather with low humidity |
What is a continental tropical air mass? | Hot, dry air masses that form mostly in summer over dry areas of the Southwest and northern Mexico. Hot, dry weather |
Maritime tropical | Warm, humid air masses that form over the Pacific ocean in the summer. Bring summer showers and thunderstorms and heavy rain or snow in the winter. |
How do air masses move? | They are commonly moved by the prevailing westerlies and jet streams |
What are prevailing westerlies? | Major wind belts over the continental United States. Generally push air masses from west to east. |
What are jet streams? | Bands of high-speed winds about 10km above Earth’s surface. Generally blow from west to east, carrying air streams along their tracks. |
What are fronts? | The boundary where air masses with different temperatures and humidity meet. Colliding air masses. |
What are cold fronts? | Forms when a faster cold air mass runs into a slower warm air mass, pushing the warm air upward along the leading edge of the colder air. |
What type of front arrives quickly and causes abrupt weather changes, including thunderstorms? | cold fronts |
What are warm fronts? | A fast-moving warm air mass overtakes a slower cold air mass. The warm air moves over the cold air. May be accompanied by clouds and precipitation. |
Which type of front arrives slowly and may cause the weather to be rainy or cloudy for several days? | warm fronts |
What are occluded fronts? | Where a warm air mass is caught between two cooler air masses. The temperature near the ground becomes cooler and the warm air is cut off. Most complex weather situation. May be cloudy and rain or snow may fall. |
What are stationary fronts | Warm and cool air meet but neither can move the other. Where the two meet, water vapor in the warm air condenses into rain, snow, fog, or clouds. If it stalls, it may bring many days of clouds and precipitation |
What type of air is denser? | cold air |
What are cyclones? | A swirling center of low air pressure |
What is indicated by a circled L on a weather map? | Cyclones. The L stands for low pressure. |
What is indicated by a circled H on a weather map? | Anticyclones. The H stands for high pressure. |
What are anticyclones? | Opposite of a cyclone. High pressure centers of dry air. |
What are storms? | A violent disturbance in the atmosphere. Involve sudden changes in air pressure, which cause rapid air movements |
What are winter storms? | Precipitation that falls as snow. Most precipitation begins in clouds as snow. If the air is colder than 0 degrees C. all the way to the ground, precipitation falls as snow. |
What are thunderstorms? | A small storm often accompanied by heavy precipitation and frequent thunder and lightning. |
Where do thunderstorms form? | In large cumulonimbus clouds, also called thunderheads. |
When do thunderstorms typically form? | On hot, humid afternoons or evenings when warm air is forced upward along a cold front. |
What is lightning? | A sudden spark, or electrical discharge, as positive and negative electrical charges jump between parts of a cloud, between nearby clouds, or between a cloud and the ground. |
What causes thunder? | The sound of the explosion causes by a lightning bolt rapidly heating and expanding the air around it. |
What is a hurricane? | A tropical cyclone with winds of 119 km/h or higher. |
Where does a hurricane draw its energy from? | the warm, humid air at the ocean's surface. |
Where are the winds strongest in a hurricane? | in a narrow band around the storm's center, called the eye. |
How long can hurricanes last? | a week or more. |
How does a hurricane form? | It begins over ocean water as a low-pressure area or tropical disturbance. As it grows in size and strength, it becomes a tropical storm, which may then become a hurricane. |
What is a storm surge? | A dome of water that sweeps across the coast where the hurricane lands. |
What causes a storm surge? | The high winds of the hurricane raise the level of water above the normal sea level. |
What is a tornado? | A rapidly spinning column of air that reaches down from a thunderstorm to touch Earth’s surface. |
Where do tornadoes form? | in thick cumulonimbus clouds. |
When do tornadoes typically develop? | When thunderstorms are likely or in any situation involving severe weather. Spring and early summer is most common. |
How big are tornadoes? | Only a few hundred meters across? |
How long do tornadoes last? | They are brief but deadly. |
What is a water spout? | A tornado that occurs over a lake or ocean |
What is the Enhanced Fujita Scale? | Ranks tornadoes by the amount of damage they cause. Devised by Dr. T. Theodore Fujita. |
What percentage of tornadoes are EF4 or EF5? | About 1%. |
What kind of damage occurs during an EF0 tornado? | branches broken off trees |
What kind of damage occurs during an EF1 tornado? | mobile homes overturned |
What kind of damage occurs during an EF2 tornado? | trees uprooted |
What kind of damage occurs during an EF3 tornado? | roofs and walls torn down |
What kind of damage occurs during an EF4 tornado? | houses leveled |
What kind of damage occurs during an EF5 tornado? | houses carried away |
Which type of tornado causes the most extreme damage? | EF5 |
What is a meteorologist? | A scientist who study and try to predict the weather |
What does the National Weather Service use to gather data? | Balloons, satellites, radar, and surface instruments |
What do meteorologists use to analyze weather data? | Maps, charts, computers, and other technology. |
What are automated weather stations? | Weather stations that gather data from surface locations for temperature, air pressure, relative humidity, and rainfall, and wind speed and direction. |
What are weather balloons? | Carry instruments into the troposphere and lower stratosphere to measure temperature, air pressure, and humidity. |
What are weather satellites? | Orbit Earth in the exosphere and use cameras to take images of Earth’s surface, clouds, storms, and snow cover. Also collect data on temperature, humidity, solar radiation, and wind speed and direction. |
What are computer forecasts? | process weather data quickly to help forecasters make predictions. |
What are weather service maps? | Data from many local weather stations all over the country and assembled into weather maps. |
What are isobars? | Lines joining places on the map that have the same air pressure. The numbers are pressure readings. |
What are isotherms? | Lines joining places that have the same temperature |
What is the butterfly effect? | A small change in the weather today can mean a larger change in the weather a week later. |
What are stratus clouds? | layered clouds usually cover all or most of the sky |
What are cirrus clouds? | wispy, feathery clouds that form at high altitudes |
What are cumulus clouds? | Look like cotton. Form less than 2 km above the ground. |
What are cumulonimbus clouds? | Towering clouds with flat tops that often produce thunderstorms. |
What are nimbostratus clouds? | low-level clouds accompanied by light rain or snow. |