1 WEATHER CAN BECOME EXTREME Will it rain Will it be warm What should I wear Weather is often the first thing people think about every day Weather is the state of the atmosphere at a particular time and place In most places the weather can change from season to season and day to day It may even change from hour to hour The National Weather Service NWS in the United States helps people prepare for the weather The NWS uses radar on the ground It has satellites in space to gather weather information It also uses weather balloons to measure air temperature pressure wind and humidity Together all this information gives them weather forecast reports Forecasts may predict sun and warm temperatures Or they might predict extreme weather The weather forecast lets drivers know about dangerous weather 4
THINK ABOUT IT What is your weather today Is it normal or extreme Use these pages definition of extreme weather to help you decide Give two examples of how your weather is normal or extreme The NWS also issues weather watches and warnings to alert people of dangerous weather A watch means conditions outdoors may possibly turn dangerous People should keep a watchful eye on the sky A weather warning means dangerous weather is occurring now ccurring now People should seek shelter and take other safety steps Weather warnings are very helpful in the case of extreme weather Extreme weather is weather that is more violent or different from normal Heat waves high h winds and extremely cold ld s winters are all examples of extreme weather Some me 1,000 Average number of weather watches the NWS issues each year Weather is the state of the atmosphere on a given day Weather can change from season to season day to day and hour to hour The National Weather Service provides forecasts Weather watches and warnings help people stay safe during extreme weather hurricanes may also be considered hurricanes may als extreme While extreme weather extreme While ex may not happen very often it may not happen causes damage to buildings and causes damage roads and puts people at risk roads and puts Heat waves can be harmful to human health 5
2 A THUNDERSTORM IS AN ELECTRICAL STORM Approximately 18 million thunderstorms occur each year At least 2,000 thunderstorms are in progress at any given time on Earth’s surface Thunderstorms bring much-needed rain to many places They also produce electricity A thunderstorm is a rainstorm that produces lightning thunder wind and sometimes hail Some severe thunderstorms can cause tornadoes A thunderstorm forms when warm moist air rises from the earth As the air rises it cools down Cool air holds less water than warm air Thunderstorms bring rain to farm fields 6 THE WORLD’S LARGEST HAILSTONE Hailstones are a form of frozen precipitation They fall in hard irregularly shaped balls They usually range from the size of a penny to the size of a softball Larger hailstones can cause damage to crops windows and cars The largest can kill animals and humans The largest hailstone on record fell in Vivian South Dakota in 2010 It was almost the size of a bowling ball
Lightning strikes in rural areas and in cities Some cool air turns into clouds Eventually the cool air in the clouds falls as precipitation Thunderstorms also produce lightning Lightning is a giant electrical spark in the sky It heats 10 Number of minutes a typical thunderstorm takes to develop About 2,000 thunderstorms are in progress at any given time on Earth Thunderstorms can cause lightning thunder wind hail and even tornadoes Lightning is a giant electrical spark in the sky and is extremely powerful the air five times hotter than the surface temperature of the sun Most lightning viewed by people is a spark between the sky and the ground Lightning can also travel between clouds During a thunderstorm lightning often targets the tallest object in an area Lightning is extremely powerful Lightning that strikes the ground can deliver enough electricity to light a 100-watt light bulb for up to three months It can cause severe electrocution in humans and animals Approximately 100 people die every year in the United States from lightning strikes During a thunderstorm with lightning people should find shelter They should stop outdoor activities such as soccer and swimming until the storm passes 7
