9.3

Radar

(short for "radio detection and ranging") system that uses radio waves to detect objects and measure their distance

Hectopascal

(symbol hPa) metric pressure unit equal to 100 Pa or 1 mbar used to measure air pressure

Millibar

(symbol mbar) pressure unit used to measure atmospheric pressure; Equal to 1/1000 bar or one hectopascal

What unit of pressure is approximately equal to atmospheric pressure

1 bar

Explain the relationship between bars, millibars, and hectopascals.

1 bar = 100 kPa; 1 millibar = 100 Pa; 1 hectopascal = 100 Pa

feature seen in radar images that indicates the location of a mesocyclone

A hook-like echo called a hook echo

Describe the relationship between atmospheric pressure and weather conditions.

Falling atmospheric pressure usually indicates bad weather, and rising pressure usually indicates good weather.

Define radiosonde.

Instrument that simultaneously measures and transmits meteorological data from a weather balloon to weather stations

lines of equal pressure

Isobars

What three things can Doppler radar measure

Precipitation, wind speed, wind direction

What type of hygrometer measures humidity using the cooling effect of evaporating water

Psychrometer

Device that uses radio waves to detect objects and measure their direction

Radar

What feature of a surface weather chart shows the conditions measured at a particular weather station

Station model

What device do meteorologists use to process all of the information they collect about weather conditions

Supercomputer

Why are supercomputers required to produce accurate long-term weather forecasts?

Supercomputers are capable of rapidly performing complex calculations. These computers keep track of weather conditions all over the world from sea level to beyond the stratopause.

When the relative humidity is 100%, the wet-bulb and dry-bulb temperatures given by a psychrometer are the same. Why is this?

The 100% humidity means that less water will evaporate from the wet gauze of the wet-bulb and there will be no pronounced cooling effect.

How does the Doppler effect help meteorologists forecast the weather?

The Doppler effect can be used to show how quickly the wind and storms are moving.

How does a bimetallic strip thermometer work?

The bimetallic strip is made of two thin strips of different metals. Because these two metals expand at different rates when heated, the strip bends in one direction when the temperature rises and in the opposite direction when the temperature falls.

What is anemometer used for

To measure wind speed

What is a maximum-minimum thermometer used for

To record the highest and lowest temperatures of the day in night during a particular.

How are weather satellites useful to meteorologists?

Weather satellites can determine the temperature of the ground, the oceans, or the upper atmosphere; measure high-altitude wind speeds, precipitation, and relative humidity; and even determine the chemical composition of the atmosphere at various altitudes.

Thermograph

a special type of thermometer that records temperature changes overtime

Isobar

any of the lines on a weather map that connect areas of equal pressure

Isotherms

any of the lines on a weather map that connect areas of equal temperature

Aneroid barometer

barometer that uses a flexible, airtight metal box to measure changes in atmospheric pressure

Transmissometer

device that measures visibility

Supercomputers

extremely powerful computer capable of rapidly performing complex calculations

Visibility

farthest distance at which objects can be distinguished

Hygrometer

general term for an instrument used to measure relative humidity

Station model

grouping of numbers and symbols on a weather map that is used to represent conditions at each weather station

Bar

in meteorology, a unit of pressure equal to 100 kilopascals

Barograph

instrument that records changes in air pressure overtime

Radiosondes

instrument that simultaneously measures in transmits meteorological data from a weather balloon to weather stations

Thermometer

instrument used to measure air temperature

Barometer

instrument used to measure atmospheric pressure

Ceilometer

instrument used to measure the distance from the ground to the base of clouds

Anemometer

instrument used to measure wind speeds near the earth's surface

Lines of equal heat

isotherms

Surface weather charts

map that gives a summary of the weather conditions throughout the entire country at a single point of time

Bimetallic strip

metal strip consisting of two thin strips of different metals bound together, used to measure temperature

Mercury barometer

oldest type of barometer, which measures air pressure by the height of a mercury column the air will support

Rain gauge

open, cylindrical glass jar with a ruler on the side that is used to measure rainfall

Weather forecasts

prediction of what the weather will be like in the near future

Weather satellite

satellite used by meteorologists to track weather around the globe

Weather vane

simple device that measures wind direction by pointing into the wind

Sounding rockets

small, inexpensive rocket used to measure high-altitude conditions

Maximum-minimum thermometer

thermometer that records the highest and lowest temperatures of the day and night during a particular period

Electrical thermometer

thermometer that works by measuring the effect of temperature on a special electrical circuit

Stevenson screen

type of box-like shelter with slatted sides in a slatted base to allow air to freely flow through the shelter and reached the meteorological instruments inside

Psychrometer

type of hygrometer that uses the cooling effect of evaporation to measure the humidity by comparing the temperatures of a wet-bulb thermometer and a dry-bulb thermometer

Doppler radar

type of radar that uses the Doppler effect to measure both precipitation and the speed and direction of winds

Weather balloons

unmanned helium or hydrogen balloon carrying instruments to measure high-altitude weather conditions

Automatic weather stations

weather station that allows atmospheric conditions to be monitored without a meteorologist at the site

Give two signs of an approaching warm front and two signs of an approaching cold front.

An approaching warm front is signaled by cirrus and cirrostratus clouds, leading to altostratus, nimbostratus, and stratus clouds. An approaching cold front starts with altocumulus and stratocumulus clouds, soon giving way to rain-bearing nimbostratus and cumulonimbus clouds.