20-3 Flashcards
what are thunderstorms? how can they be produced?
small storms with thunder and lightning, heavy precipitation, winds, hail. Can be produced by one cumulonimbus cloud and influence small area, or associated with clusters of cumulonimbus clouds stretching many km along cold front
where do thunderstorms occur?
most occur in tropics where warmth, moisture, and instability are common
how do thunderstorms develop?
when warm humid air rises in unstable environment
what are the 3 stages of thunderstorm development?
cumulus stage, mature stage, and dissipation stage.
what is the cumulus stage?
On hot, humid afternoons or along a cold front, warm air rises, creating strong updrafts. Each new surge pushes higher, forming a tall cumulonimbus cloud.
what is the mature stage?
most active stage happens within an hour, as updrafts can no longer hold the heavy water droplets and ice crystals. This causes heavy rain, strong winds, lightning, and sometimes hail.
what is the thunderhead?
downdrafts along back of cloud, updrafts along front
what is the dissipation stage?
Mostly downdrafts; rain and cold air cool the storm, causing it to weaken. As it moves, it may bring in warm, humid air, forming new cumulonimbus clouds.
What causes lightning and how does it form?
Lightning happens when positive and negative charges build up, creating a sudden spark that charges jumps within a cloud, between clouds, or from a cloud to the ground.
Why does thunder occur and why do we see lightning before hearing thunder?
Thunder is the sound of the explosion caused by rapidly heated air from the lightning bolt. Light travels much faster than sound, so we see lightning before we hear thunder.
what are fulgurites?
fossilized lightning, may form when lightning bolt melts the sand it strikes and cools so quickly so no time for crystals to form, glass tube structure
what is a tornado?
violent, whirling funnel-shaped cloud and wind called a vortex moves in narrow path over land
Reaches down from cumulonimbus cloud to touch Earth’s surface, brief but deadly
what is waterspout?
term given to tornado over a lake/ocean
where do tornadoes most frequently occur?
Florida, Southern and Central Great Plains, especially in early spring.
how do tornadoes develop?
Forms when warm, humid air from the Gulf of Mexico moves north and meets cold, dry air from Canada. The cold air pushes the warm air up, creating a line of thunderstorms moving from southwest to northeast.
what are mesocyclones?
precursor to a tornado - three stages
what are the three stages of a mesocyclone?
- Stronger winds aloft cause lower winds to roll
- Updrafts tilt the rolling air so it becomes nearly vertical
- When the rotating air becomes completely vertical the mesocyclone is established
How does tornado intensity form?
Warm air rises, creating low pressure. Winds blow in, forming wind shear and violent rotation. Air pressure drops quickly
What happens when a funnel cloud reaches the ground?
If a funnel cloud reaches the ground, it becomes a tornado, picking up dirt and debris, making it appear dark gray or black.
What kind of damage can a tornado cause?
updraft is so strong that it can rip apart buildings and trees, explode structures, lift and move animals, cars, and houses, making tornadoes one of the most destructive storms.
What is the role of the Storm Prediction Center (SPC) in tornado warnings?
The SPC monitors different types of severe weather and provides timely and accurate forecasts and watches for severe thunderstorms and tornadoes.
what is the difference between a tornado watch and warning?
Tornado watch: alerts people of possible tornado
Tornado warning: tornado sighted in an area/indicated by weather radar
what are hurricanes?
Hurricanes are spinning tropical cyclones with winds of at least 119 km/h. They form in warm, rainy tropical areas and can cause powerful waves, strong winds, and severe flooding, leading to costly and deadly damage.
where do hurricanes form?
starts to form at 5 to 20 degrees north and south of the equator because warm ocean water is there, forms in the late summer when water temperatures are warm enough to provide necessary heat and moisture to the air
what powers hurricane development?
Hurricanes are fueled by energy released when large amounts of water vapor condense.
how does a hurricane begin to form?
It begins as a tropical disturbance with clouds, storms, and low pressure. Warm, moist air moves in, rises, and forms a ring of storm clouds.
what is an eyewall?
donut-shaped wall with the strongest winds, and heaviest rain. Curved cloud bands extend outward, and rising air at the top moves away, allowing more air to flow in at the surface.
what is an eye?
very center of the storm with no rain and winds are calm, air in the eye descends, warms, low relative humidity, warmest part of the storm
what is a storm surge? when does it have greater devastation? when does it create more friction?
The most damage from a hurricane, comes from a dome of water that sweeps across the coast when the eye hits land. It’s worse if it coincides with spring tide. As the hurricane moves over land or cooler water, it weakens, and friction from the land slows the winds.
what are the 2 sources the National Weather Service depends on for its information?
- Data collected from Earth’s surface
- Data collected from the upper atmosphere using weather balloons and satellites
what do station models give?
give information gathered at one of many locations on map
what are weather balloons?
carry instruments high into troposphere and lower stratosphere; measures temperature, air pressure, humidity
what are weather satellites?
orbits Earth in the exosphere, cameras take images of Earth’s surface, clouds, storms and snow coverage, transmitted back to Earth for meteorologists
