Measuring WeatherLO: To know the purpose of the following instruments and how to use them.

Stevenson ScreenRain GaugeBarometers Wind VaneAnemometerSixs Thermometer (Maximum-Minimum Thermometer)Hygrometer (Wet and dry bulb thermometer)

Task oneWhat is a Stevenson's screenMake a list of instruments you may find in a Stevensons screenWhere would you locate a Stevensons screen and why?Task TwoFor the following instruments you need to use your handout to:Rain GaugeBarometers Wind VaneAnemometerSixs Thermometer (Maximum-Minimum Thermometer)Hygrometer (Wet and dry bulb thermometer)write what it measures and a brief description, instructions on how to locate it.

TemperatureMax Min ThermometerSixs ThermometerMax-MercuryMin-AlcoholMeasures shade temperature (Stevensons screen)Read off at bottom of the index (reset with magnet)Read at eye levelMeasured in C

Humidity

Wet/Dry Bulb thermometerHygrometerWick and reservoir of water

Comparison tablesCalculate depression of wet bulb (Dry Wet)Read off table

Measures in shade (Stevensons screen)Units = % Relative humidity

Wind SpeedAnemometerCups or blades

Clear unobstructed location

Km per hour

Wind DirectionWind VaneRecorded on Wind Rose

Compass Directions

Beaufort Scale.Another way of measuring wind speed by looking at the effect of wind on the environment.

Wind ForceDescriptionSpeed Specifications kphknots 0Calm00Smoke rises vertically1Light Air1-51-3Direction shown by smoke drift but not by wind vanes2Light Breeze6-114-6Wind felt on face; leaves rustle; wind vane moved by wind3Gentle Breeze12-197-10Leaves and small twigs in constant motion; light flags extended4 Moderate Breeze20-2811-16Raises dust and loose paper; small branches moved.5Fresh Breeze29-3817-21Small trees in leaf begin to sway; crested wavelets form on inland waters.6Strong Breeze38-4922-27Large branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty.7Near Gale50-6128-33Whole trees in motion; inconvenience felt when walking against the wind.8Gale62-7434-40Twigs break off trees; generally impedes progress.9Strong Gale75-8841-47Slight structural damage (chimney pots and slates removed).10Storm89-10248-55Seldom experienced inland; trees uprooted; considerable structural damage11Violent Storm103-11756-63Very rarely experienced; accompanied by widespread damage.12Hurricane118 plus64 plusDevastation

Air PressureAneoid Barometer

BarographPlots changes in pressure

MillibarsMeasured in shade (Stevensons screen)

RainfallRain gauge

Siting factorsClear view of skyRecessed into groundApprox 30cm above groundGrassy surface (avoid splash back)Read off at eye level

Regular intervals (24hours)

SunshineSunshine recorderBurns a timelineTraces sun shine not hours of daylight

Glass ball focuses lightBurns line onto card

Units = Hours

Cloud Cover ChartCloud MirrorDivide mirror into 16 equal squaresLay mirror on ground with clear view of skyEstimate cover

Units = Oktas

Stevensons ScreenHouses temperature / humidity /pressure instrumentsFeaturesInsulated roofPainted white to reflect heatLouvered (slatted) sides aid air circulationLocated 1.25-2m above ground Locate in safe placeLocate away from buildings or trees

Cloud over ChartDifferent cloud types are a sign of different weather conditions. Certain cloud types will produce rain such as Nimbostratus and Cumulonimbus.Others show a warm front, which will bring rain, is approaching such as Altostratus.

LO: Describe the main types of cloud and be able to estimate the extent of cloud cover.

Pg 87 of handouthttp://www.youtube.com/watch?v=FMagDRCpJ14

Cloud cover is measured in Oktas or Eighths. Today there are _______ Oktas (or Eighths) of cloud.

We know there are many different types of cloud, because not all cloud looks the same.You might see more than one of these types of clouds in the sky all at once.

These are the main types of cloud:Cirrus clouds are wispy, like a lock of hair, and are high up.Cumulus means heap, cumulus clouds look a bit like cotton wool ballsStratus clouds are layers, and are middle to low clouds.Cumulonimbus clouds are tall and dense, usually resulting in rain or storms.

Any cloud with the word cirro or cirrus is a high cloud.Any cloud with the word alto in it is about in the middle.Any cloud with nimbo or nimbus added onto it means it is producing precipitation.

Add labels to your diagram of the clouds.

Cumulus

Cumulonimbus

Cumulonimbus

Cumulus

Cirrus

Stratus

Cumulus

Stratus

Cirrus

Cumulus

Cirrus

Stratus

Cumulonimbus

Cumulus

Cirrus

Now answer the following questions:

What are clouds?What is cloud cover measured in?What are the three main cloud types?What name do high level clouds begin with?What types of clouds does convectional rainfall cause?

Type of CloudAppearanceAltitude (height)Cumulo-nimbus =ThunderheadsCan cause lightning, thunder, hail, strong rains, strong winds, and tornadoesNear ground up to 75,000 feet (Vertical clouds)Cirro-stratusThin, wispy, appears in sheets. Located above thunderheadsAbove 18,000 feet (High-altitude clouds)CirrusThin, wispy, filamentous, or curlyAbove 18,000 feet (High-altitude clouds)Cirro-cumulusSmall, puffy, patchy and/or with a wavelike appearanceAbove 18,000 feet (High-altitude clouds)Alto-cumulusMedium-sized puffy, patchy, scattered clouds - often in linear bands6,500 - 20,000 feet (Middle-altitude clouds)Alto-stratusThin, uniform6,500 - 20,000 feet (Middle-Alttude clouds)Strato-cumulusBroad and flat on the bottom, puffy on top, Below 6,500 feet (Low-altitude clouds)CumulusPuffy and piled up.Below 6,500 feet (Vertical clouds)StratusUniform, flat, thick to thin layered clouds will ill-defined edgesBelow 6,500 feet (Low-altitude clouds)Nimbo-stratusUniform, dark, flat, low, featureless clouds that produce precipitationBelow 6,500 feet (Low-altitude clouds)

alto-cumulus - Middle-level, medium-sized puffy clouds. alto-stratus - Middle-level, layered clouds. cirro-cumulus - High-altitude, small, wispy, patchy, puffy clouds. cirro-stratus - High-altitude, thin, wispy clouds in layers. cirrus - High-altitude, thin, wispy clouds. cumulo-nimbus- Large, dense, towering clouds that cause thunderstorms. cumulus - Low, puffy clouds. fog - Ground-hugging clouds. nimbo-stratus - Low, dark, rain cloud. stratus - Low, layered, horizontal, wispy clouds with a flat base. strato-cumulus - Low clouds, broad and flat on the bottom, puffy on top (higher than cumulus and lower than altocumulus