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Weather!Chapter 7 sections 1&4
• Measuring and recording!
• Meteorologists use a variety of weather instruments to more accurately forecast the weather.
• Write down the ones you know.
Measuring Relative Humidity• The amount of moisture that is in the air is a
major factor that influences our weather.
• Moisture in the air is known as humidity
• Relative humidity is the comparison of the amount of moisture present in the air at a certain temp. compared to the amount it COULD have in the air at that temp.
• This comparison is given as a percent (%)
• Do you know what tool is used to measure Relative Humidity????
Relative Humidity
•
Psychrometer measures in percentages (%)
Hygrometer measures in percentages (%)
Measuring Rain
• Meteorologists keep up with and record the amount of precipitation that falls.
• These measurements are given in inches or centimeters.
• Why would meteorologist want to keep with that?
Rainfall
• A Rain gauge is used to measure the amount of precipitation that has fallen.
Measuring Wind Speed• Wind (air) speed is also an influence in the
weather.
• It could signify a major temperature change, which results in storms or severe weather.
• Wind speed is measured in Mph (miles per hour) or kmph (kilometers per hour)
Wind Speed
• An anemometer is used to measure wind speed.
• As the wind spins the cups the turning is transmitted to dials that show how fast the wind is blowing.
Measuring Air pressure
• As different air masses move across the regions of our Earth they produce characteristic types of weather.
• These air masses are known as either Cyclones (low pressure systems) or Anticyclones (high pressure systems)
Air pressure• Barometers measure air
pressure.
• Mercury Barometers measure the amount of pressure the air exerts on a column of Mercury, the level of mercury goes up when the air pressure is high and goes down when its low.
• Barometric pressure can be measured in inches, millimeters, or millibars.
Air pressure• Aneroid Barometers contain NO liquid.
• It depends on a vacuum box to movie in and out as air pressure changes.
• As the vacuum box moves in and out the movement causes a dial to fluctuate.
• This barometer pressure
is also measured in in, mm,
millibars
Measuring Temperature
• What tool measures the temperature of the air? – Thermometer
• What is the temperature measured in?– Celsius C– Fahrenheit F
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