Weather Instruments How do they help in predicting weather?

Temperature A meteorologist would use a thermometer to measure the local temperature. Generally, there is a high temperature and low temperature predicted for each day. A mathematical formula is used to help make these predictions as accurate as possible. Also, a high and low temperature is recorded each day. The low generally occurs in early morning hours and the high in late afternoon hours.

Thermometer Measures temperature Scales used: degrees Fahrenheit (F) or degrees Celsius (C)

Precipitation Precipitation is collected in a rain gauge. It then tells a meteorologist how much it has rain or snowed in an area.

Rain Gauge Measures amount of precipitation Scale: collected in inches (in.) or centimeters (cm)

Air Pressure The difference in air pressure results in wind. Fronts then move as the wind pushes them. Air will move from an area of high pressure to an area of low pressure. As winds blow into a low pressure area, air moves upward causing clouds to form leading to precipitation. In general, weather improves when pressure increases and worsens when pressure decreases.

Barometer Measures Air Pressure Scale: Inches Some barometers use mercury (a liquid metal) and when the pressure pushes on the air in the tube of metal, the mercury will rise. More commonly used today are aneroid barometers which do not have a tube of mercury but instead in a small box. The difference in air pressure causes this small box to change shape and move a needle on a gauge that indicates the air pressure. Normal air pressure is between 28 and 31 inches. Sudden changes in the air pressure means that the weather will be changing.

Barometer – measures air pressure

Humidity Humidity is the amount of moisture in the air. As more water evaporates, the humidity gets greater. Humidity is measured with a tool called a hygrometer.

Hygrometer Measures: Humidity Measures: Humidity Recorded in percents (%) Recorded in percents (%) 100 % humidity is raining; 10 – 30% humidity means it’s relatively dry 100 % humidity is raining; 10 – 30% humidity means it’s relatively dry

Wind Wind is simply just moving air. It moves because of a difference in air pressure or a difference in temperature. Wind direction and wind speed in measured in order for meteorologists to determine the way a front will move and how quickly it will it will move. So, two instruments are used to measure wind: wind vane and an anemometer.

Wind Vane Determines wind direction – which way the wind is blowing from Scale used: cardinal and intermediate directions The pointer or the arrow generally turns into the wind.

Anemometer Measures wind speed – how fast is the wind blowing Scale used: knots or miles per hour

Beaufort Scale = used in measuring wind Beaufort number Wind speed MPH Description Sea conditions Land conditions Land conditions 0<1calmflatcalm 11-3 light air ripples without crests wind visible in smoke 24-7 light breeze small wavelets leaves rustle gentle breeze large wavelets smaller twigs in constant motion moderate breeze small waves small branches begin to move fresh breeze moderate longer waves small trees sway strong breeze large waves with foam crests large branches move near gale sea heaps up and foam begins to streak whole trees in motion gale moderately high waves with breaking crests twigs broken from trees severe gale high waves with dense foam light structure damage storm very high waves; the sea surface is white trees uprooted; considerable structure damage violent storm except ally high waves widespread structural damage hurricane sea completely white with driving spray massive damage to structures

Force 0

Force 1

Force 2

Force 3

Force 4

Force 5

Force 6

Force 7

Force 8

Force 9

Beaufort Scale Force 10

Beaufort Scale Force 11

Name that Instrument

thermometer

wind vane

barometer

anemometer

rain gauge