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Measuring instruments of weather


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Measuring instruments of weather

  1. 1. By Aakriti
  2. 2. Weather The weather is all around us, all the time. It is an important part of our lives and one that we cannot control. Instead the weather often controls how and where we live, what we do, what we wear and what we eat. Someone who studies the weather is called a meteorologist. Weather predictions are made by forecasters who you see on television.What is weather??? Weather is the day-to-day conditions of a particular place.
  3. 3. Forecasting weather On television and radio, we often hear weatherforecasts predicting the weather. They are not fortunetellers but base their reports on the collection of a largeamount of scientific information. Satellites have been putinto orbit around the earth to measure the amount ofheat from the sun. We can see pictures from thesatellites on the television. All these observations areused to produce the weather forecast. Weather forecasting is one of those rare activities thatunite nations in a common effort from which peopleworld wide benefit. Through weather satellites andcombined effort of more than 180 countries of the WorldMeteorological Organization, we can track the forces thatcontrol our weather and forecast their behavior up to a
  4. 4. ClimateClimate is often spoken about at the same time asweather, but it is something quite different. The climate isthe common, average weather conditions at a particularplace over a long period of time (for example, more than30 years). We learn about different climates around theworld. Deserts have a hot and dry climate while theAntarctic has a very cold and dry climate.
  5. 5. Weather There are number of important elements of weather that have to be measured and recorded hourly or daily.1.Temperature2. Wind3. Cloud4. Sunshine5. Visibility6. Humidity7. Pressure8. Precipitation
  6. 6. Temperature Temperature is the measure of how coldor hot somewhere is. Temperature isusually higher during the day than at night.Rural areas (the countryside) are oftencooler than towns and cities. This isbecause there are more buildings andfactories ( known as heat islands) whichabsorb heat during the day, releasing itslowly at night and warming thesurrounding air.
  7. 7. Wind The earth’s atmosphere and air around us isalways moving. Wind is simply moving air.Sometimes it moves slowly creating a gentlebreeze. Other times it can move faster creatingstronger, more powerful winds. We cannot seethe wind, but we can see what it does to treesoutside and kites on the beach. If you areoutside on a windy day you can sometimes feelthe wind on your face. It may be so windy that itis difficult to walk.Both the direction and speed ofthe wind should be measured for weatherobservations.
  8. 8. Cloud Clouds are made up of millions of tinywater droplets. Clouds are made whenquite warm, moist air rises into the skywhere it cools down and condenses.Clouds can form in a few minutes or overa number of hours. There are manydifferent types of cloud and looking atthem can help you to predict the weather.
  9. 9. Sunshine The amount of sunshine we havedepends on latitude and how much cloudthere is in the sky. In some of the worldsdeserts the number of sunshine hours isvery high, more than 3,600 hours eachyear. In the Eastern Sahara desert, thesun is covered by clouds for less than 100hours a year. In Britain we have from1,850 hours in Southern England to 1,200hours in North Scotland. There is usually
  10. 10. Visibility We have all seen a foggy day when it is difficult tosee, and no matter how fast you run the fogseems just as thick and just as far away from you.This is because there is no insulating blanket of airabove to keep the earths heat in. The air closestto the ground cools rapidly, with all the watervapour in the air condensing as tiny floatingdroplets of water. Visibility is simply how far you can see. Inweather terms it is how clear the atmosphere andair are, taking into account fog, mist and urbanpollution. Fog and mist are like clouds on theground. They are made up of lots of tiny waterdroplets, which is why you can sometimes get wet
  11. 11. Humidity Humidity is how much water vapour is inthe atmosphere. Like a sponge, the air isalways evaporating and storing water fromrivers, lakes and oceans. In tropical partsof the world, warm air is able to hold morewater vapour and humidity is higher as aresult.
  12. 12. Pressure Pressure is the weight of the atmosphereon the earth’s surface. This atmosphericpressure is lower at the top of mountainsand highest at sea level. This is beacuseall the air above the sea pushes down onits surface. Rapid drops in air pressuremean unstable conditions and a storm ison its way, while rises in pressure meanconditions are more stable and fairweather is returning.
  13. 13. Precipitation Precipitation is the release of water from the atmosphere to the earth’s surface as a solid or liquid. It includes rain, snow, hail, sleet and dew.RAIN In the British Isles, rainfall is a very common type of weather. Rain starts above us when small droplets of water in the clouds join together until they get too big and heavy and fall from the clouds. However, different cloud types can produce different rainfall. Heavy rainfall after a hot summer day may fall from tall, large white,
  14. 14. PrecipitationSNOW During the winter months when temperatures are cold, (at or close to 0º Celsius) snow will fall from clouds instead of rain. Snow starts off in the same way as rain, with tiny droplets of water joining together in clouds until they are too heavy. However, when they fall it is important that the air is freezing for there to be snow. Otherwise the snowflakes will melt and become sleet or rain before they reach the
  15. 15. PrecipitationHAIL Hail falls as hailstones, which are like small balls of ice. Their diameter usually ranges from under a centimetre to 5cm. Larger hailstones can cause damage to crops and gardens, greenhouses and glass roofs
  16. 16. Measuring instruments of weatherWhy are they needed? Measuring instruments of weather are needed to measure different kinds of weather conditions accurately. There are many different types of instruments for measuring weather like- Thermometers, barometers, anemometer, rain gauge, scales etc
  17. 17. Temperature Temperature is measured using athermometer, with units in degrees onFahrenheit (ºF) or Celsius (ºC) scales. Themain type of thermometer used is theliquid-in-glass thermometer. A liquid(usually alcohol) expands depending ontemperature. It then moves up a small tubealongside a scale, from which temperaturereadings can be made. Thermometersshould be put within a Stevenson Screento stop temperature readings beingaffected by direct sunlight.
  18. 18. WindWind Direction One of the oldest pieces of equipment used to measure weather is a wind vane. This wind or weather vane is usually made from a strong material, (like metal) and placed above ground, usually on top of a building. The wind vane will show clearly the 4 principle directions of the compass: North, East, South and West, and have a moveable arm that can point in any direction. Once true north is known (using a compass), the wind direction can be found by looking at the direction the arm is pointing from. For example, air moving from east to west will create an easterly wind.
  19. 19. WindWind speed The wind speed is measured using an anemometer. Most weather stations measure wind speed using a spinning cup anemometer, which rotates depending on the wind.
  20. 20. CloudCloud can be measured through a number ofobservations. Consider whether the cloud is:HIGH(5,500-14,000 meters)Includes: Cirrus, cirrocumulus, and cirrostratusMEDIUM(2,000-7,000 meters)Includes: Altocumulus, altostratus, and nimbostratusLOW(below 2,000 meters)Includes: Stratocumulus, Stratus, Cumulus, andCumulonimbus
  21. 21. CloudAltitude Name Color Descripti Weather onHigh Thin silky Cirrus White and Fair featheryHigh Cirrocumulu Ripples/bu White Fair s mpsHigh Fat, smooth Cirrostratus Whitish transparent Worsening sheetMedium Layers and waves often Altocumulus White/grey Fair separated by blue sky
  22. 22. CloudAltitude Name Color Descripti Weather onLow Layers in Stratocum Grey/whit rounded Dry/dull ulus e rolls. No breaks.Low Thin sheet Stratus Grey Drizzle blanketing skyLow Grey/whit Puffy Cumulus Good e cloudsLow Storms.
  23. 23. Cloud The cloud types above are the most common inthe UK, though more unusual clouds maysometimes be seen. In May 2004, mammothscloud was visible at the base of a cumulonimbusformation over Broad Oak Nature Reserve. The amount of cloud in the sky is measured ineighths (or okras by meteorologists). Simpleobservation can be made such asClear - no cloud coverPartly cloudy - less than half cloud coverMainly cloudy - more than half cloud cover butwith some breaks in the cloudOvercast - complete cloud cover
  24. 24. Sunshine Hours of sunshine are usually recordedon a simple machine called apyrheliometer. also known as a Campbell-Stokes recorder. It works by using a glassball to focus the sunlight and rays onto astrip of card. As the sun moves roundduring the day, the card is scorchedcreating a record of how many sunshinehours there were.
  25. 25. VisibilityVisibility can be estimated using descriptive words such as:good, poor, foggy etc. How far you can see is also used todescribe visibility:Fog – less than 1kmPoor – 1 to 5kmModerate – 5 to 10kmGood – more than 10km Different environments around the world experiencedifferent levels of fog. People living high in the mountainsmay see fog all year. The city of San Francisco in NorthAmerica is famous for its thick mist that moves in from thePacific Ocean. In the United Kingdom we mainly see fog inautumn and winter, but some tropical parts of the worldmay never have seen fog. There are two types of fog. Click to find out more:1. Advection Fog2. Radiation Fog
  26. 26. FogAdvection Fog Forms when quite warm, moist and stable air is blown across a cooler surface (land or water). The air temperature falls until the dew point is reached and condensation occurs. Examples of advection fog include San Francisco.Radiation Fog This type of fog is a thin layer that forms because land cools down overnight. When the dew point is reached and condensation occurs, the fog moves slowly upwards. Radiation fog is common at lakes, harbours and in river valleys.
  27. 27. Humidity Relative humidity is a measure of howmuch water vapour is actually in the aircompared to how much water vapour theair could hold. This is measured using awet and dry hygrometer. This type ofthermometer has two bulbs; one is keptwet in distilled water and the other dry. Thedifference in temperature between themcan be calculated to give relative humidity.Humidity must be high for fog or clouds to
  28. 28. Pressure Atmospheric pressure is measuredwith a barometer, which can be keptindoors.
  29. 29. PrecipitationRain It is useful to measure the amount of rainfall we have, as it provides an important source of water to reservoirs giving us drinking water. Rainfall is easy to measure by recording how much water collects in a rain gauge. The rain gauge is quite accurate as long as it is set up safely at ground level in an exposed place. The amount of rainfall collected in the gauge is measured in millimetres. Rainfall data can be used to work out monthly averages and
  30. 30. PrecipitationSnow Snow cannot be measured in the same way as rain, as a normal rain gauge may get blocked. Instead, the amount of snowfall is measured by inserting a ruler into a layer of snow that is flat and has not been drifted by the wind.
  31. 31. Measuring instruments of weather So, these are the different types ofMeasuring instruments of weather that Iexplained you about. Hope you enjoyedthe ppt as much as I enjoyed making it.
  32. 32. Thank You Made By Aakriti Gupta