Earth and Space Science Chapter 9 (copy)

thunderstorms

localized storms involving lightning thunder strong winds heavy rain and sometimes hail or tornadoes

stable

under normal conditions currents of rising air are stopped by adiabatic cooling and thus do not rise to great altitudes

cumulus stage

the steady supply of warm humid air combined with the strong upward movement of the updraft forms a billowing rapidly growing cumulus cloud.

mature stage

the arrival of precipitation marks the beginning of this stage during which the thunderstorm reaches the peak of its strength

downbursts

very strong localized downdrafts can create sudden concentrated blasts of cool wind that can blow downward at 130 mph or more

microbursts

smallest and most intense downbursts that may produce winds approaching at 170 mph

dissipating stage

the stage where the cumulonimbus cloud will dissipate. The air returns to a stable state.

supercell

the most powerful type of thunderstorm, a fierce single-updraft giant, which usually occur during the spring and early summer when temperature differences are most dramatic

lightning

an abrupt discharge of electricity through the air that produces a quick flash of bright light

stepped leader

from the cloud a stream of electrons begins to move jerkily toward the ground

positive streamer

the positive charge on the ground attracted by the approaching stepped leader launches upward in this that rises to meet the stepped leader

return stroke

upward flow of positive charge which forms the brilliant flash of light that can be seen

thunder

the heat from the return stroke causes the air near the lightning bolt to expand explosively forming a shock wave of sound known as this

tornado

a narrow funnel of powerful rapidly whirling wind that stretches from a cloud to the ground

cyclones

a term that refers to any low pressure system in which winds rotate in the direction that would be caused by the coriolis effect

mesocyclone

the most powerful tornadoes are believed to form from the rotating updrafts found in many supercell thunderstorms this is such a rotating updraft

wall cloud

a large rotating cylindrical extension from the base of the supercell

Enhanced Fujita Scale

the scale that classifies tornadoes

waterspout

a tornado that forms over water, usually not associated with supercell thunderstorms unlike tornadoes

dust devil

a phenomenon similar but not a tornado, but it lacks a cloud

tropical cyclones

hurricanes and other rotating tropical low-pressure systems are also called this

hurricane

the tropical storm becomes this if it reaches 74 mph

Saffir-Simpson Hurricane Wind Scale

hurricanes are ranked using this scale

eye

the center of a hurricane which rotates counter clockwise in the Northern Hemisphere. Has calm weather

eye wall

the cylinder of thick whirling clouds and rain that sorrounds the eye

rain bands

long narrow lines of thunderstorms which carry rain in a hurricane

wind, storm surge, inland flooding

the 3 most destructive forces of a hurricane

forecast

to predict the weather

thermometer

air temperature is measured with this

thermograph

records temperature changes over time

barometer

measures atmospheric pressure

mercury barometer

the oldest type of barometer which uses mercury

aneroid barometer

a more compact and rugged type of barometer which uses a flexible air-tight metal box to measure changes in pressure

hygrometer

measures relative humidity

weather vane

a simple device that points into the wind, points into the wind

anemometer

measures wind speeds near the earth's surface

rain gauge

measures the amount of rainfall or other precipitation

Stevenson screen

a type of shelter which contains meteorological instruments and keeps them from getting damaged by weather

automatic weather stations

allow atmospheric conditions to be monitered without a meteorologist at the site (a type of weather station)

transmissometer

a device which measures visibility

weather ballons

meteorologists often measure high altitude weather conditions by attaching instruments to these unmanned helium or hydrogen ballons

radiosondes

instruments that simulataneously measure and transmit meteorological data from ballons to weather stations below

celiometer

to measure the distance from the ground to the base of clouds meteorologists use this

radar

(radio detection and ranging) an important tool of the meteorologist which uses radio waves to detect objects and measure their distance

Doppler radar

a specialized type of radar that can detect precipitation as well as the movement of small particles, which can be used to measure wind speed and direction

weather satellite

devices that circle the earth and take pictures of the weather providing meteorologists with valuable information

hurricane

intense low-pressure systems that develop in the tropics

tropical disturbances

Tropical region of low pressure without rotating winds.

Warm ocean and region where the Coriolis effect is very pronounced

two ingredients for a hurricane to form

Tropical depression

tropical cyclone with sustained winds less than 39 mph

Tropical storm

tropical cyclone with sustained winds of at least 39 mph but less than 74 mph