How do we measure weather? Flashcards
revise
What do we use to measure weather?
-Terrestrial weather stations (flat land/away from buildings)
-Weather ships/buoys (at sea/approaching coastline)
-Radiosonde balloons and Weather Planes (up in the atmosphere)
What is used to measure wind speed?
-Anemometer
-Handheld anemometers (collects information over a short period of time)
-In weather stations on a 10m pole(prevents effects from buildings/creates wind tunnels)
-Measures in knots,kph,mph
What is used to measure wind direction?
-Wind Vanes
-In weather stations (mounted on the same pole to anemometer)
-Most attached to a pole that has compass points mounted on it
-North winds are colder then south
-They use compass points to determine the direction of the wind
-The arrow points in the direction the wind has come from so we can see where it has come from so we know what weather to expect
What is used to measure sunshine/sunlight?
-Sunshine Recorder
-Records the amount of sunshine in a day
-Units are hours
-Glass balls with a metal frame behind them, attached to the frame is a piece of waxed card with a scale
-It magnifies the sun’s rays so the heat burns a mark along the card.
-Usually mounted on a pillar away from the ground to capture maximum sunlight.
-Away from objects that may shade them
What is used to measure precipitation?
-Rain Gauge
-A vessel with increments marked on it in millimetres
-Some have splash guards or mounted eye levels.
Prevents precipitation bouncing up from the ground into the gauge
-Its measured in ml so we know if it’ll just create puddles or flood banks and roads
What is used to measure temperature?
-Maximum and Minimum Thermometers
-Meteorologists are interested in this it helps them compile weather forecasts and collect data over many years to produce climate graphs
Units are degrees celsius(centigrade)
Mercury in the thermometers moves in response to changing temperatures
A metal pin is pushed up to show it every day. It is read from the bottom of the pin
What is used to measure humidity?
-Wet and Dry Bulb Thermometer
-found in the stevenson screen
-made up of 2 thermometers one is normal and the other with wet lint is attached to a bulb and a small wet reservoir to keep it damp
Will show different readings
-Difference between 2 readings is calculated and a special scale is used to calculate the percentage of moisture is present in the air
What protects thermometers?
-The Stevenson Screen
-A white box with louvered(slatted sides)
-White reflects heat preventing the thermometers getting too hot for inaccurate readings
-The slatted sides allow air to circulate around the thermometers
-Mounted 1 meter off the ground to reduce effects of gravity
What is used to measure cloud cover?
-Satellites, Radar and Meteorologists Eyes
-Radar: where cloud is forming and direction it travels
-Satellites: show it too(weather forecast)
In lots of weather stations ME do observation. Amount of cloud cover is calculated as a fraction (2 eights or 2 oktas)
-Even with radar it is important to still carry out observation because different clouds produce different weather
What is used to measure air pressure and what is it?
- Air pressure is the weight of the air squeezing down onto the Earth’s surface
-The more air that is pushing down, the higher the air pressure
-Measured in millibars(mb) barometer
-High air pressure: dry settled weather that is warm in summer
-Winter: create frost mornings and fog
-Long periods of calm,dry weather are called anticyclones
-When air rises air pressure drops
-Air rushes in from areas nearby that have high pressure to replace escaping air(causes winds) movement of air in low pressure areas
Lower pressure the higher the wind
