Measuring instruments of weather

By Aakriti

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.

Forecasting weather On television and radio, we often hear weather forecasts

predicting the weather. They are not fortune tellers but base their reports on the collection of a large amount of scientific information. Satellites have been put into orbit around the earth to measure the amount of heat from the sun. We can see pictures from the satellites on the television. All these observations are used to produce the weather forecast.

Weather forecasting is one of those rare activities that unite nations in a common effort from which people world wide benefit. Through weather satellites and combined effort of more than 180 countries of the World Meteorological Organization, we can track the forces that control our weather and forecast their behavior up to a week or more ahead. Every hour the weather reports are received from Europe and weather ships stationed in the North Atlantic Ocean.

Climate Climate is often spoken about at the same time

as weather, but it is something quite different. The climate is the common, average weather conditions at a particular place over a long period of time (for example, more than 30 years). We learn about different climates around the world. Deserts have a hot and dry climate while the Antarctic has a very cold and dry climate.

Weather

There are number of important elements of weather that have to be measured and recorded hourly or daily.

1.Temperature 2. Wind 3. Cloud 4. Sunshine 5. Visibility 6. Humidity 7. Pressure 8. Precipitation

Temperature Temperature is the measure of how cold

or hot somewhere is. Temperature is usually higher during the day than at night. Rural areas (the countryside) are often cooler than towns and cities. This is because there are more buildings and factories ( known as 'heat islands') which absorb heat during the day, releasing it slowly at night and warming the surrounding air.

Wind The earth’s atmosphere and air around us is

always moving. Wind is simply moving air. Sometimes it moves slowly creating a gentle breeze. Other times it can move faster creating stronger, more powerful winds. We cannot see the wind, but we can see what it does to trees outside and kites on the beach. If you are outside on a windy day you can sometimes feel the wind on your face. It may be so windy that it is difficult to walk.Both the direction and speed of the wind should be measured for weather observations.

Cloud Clouds are made up of millions of

tiny water droplets. Clouds are made when quite warm, moist air rises into the sky where it cools down and condenses. Clouds can form in a few minutes or over a number of hours. There are many different types of cloud and looking at them can help you to predict the weather.

Sunshine The amount of sunshine we have depends

on latitude and how much cloud there is in the sky. In some of the world's deserts the number of sunshine hours is very high, more than 3,600 hours each year. In the Eastern Sahara desert, the sun is covered by clouds for less than 100 hours a year. In Britain we have from 1,850 hours in Southern England to 1,200 hours in North Scotland. There is usually more sunshine where atmospheric pressure is higher.

Visibility We have all seen a foggy day when it is difficult to see, and

no matter how fast you run the fog seems just as thick and just as far away from you. This is because there is no insulating blanket of air above to keep the earth's heat in. The air closest to the ground cools rapidly, with all the water vapour in the air condensing as tiny floating droplets of water.

Visibility is simply how far you can see. In weather terms it is how clear the atmosphere and air are, taking into account fog, mist and urban pollution. Fog and mist are like clouds on the ground. They are made up of lots of tiny water droplets, which is why you can sometimes get wet when walking through fog. When there is a light breeze, clear skies and damp air, moisture in the air condenses near the ground making fog or mist.

Humidity Humidity is how much water vapour

is in the atmosphere. Like a sponge, the air is always evaporating and storing water from rivers, lakes and oceans. In tropical parts of the world, warm air is able to hold more water vapour and humidity is higher as a result.

Pressure

Pressure is the weight of the atmosphere on the earth’s surface. This atmospheric pressure is lower at the top of mountains and highest at sea level. This is beacuse all the air above the sea pushes down on its' surface. Rapid drops in air pressure mean unstable conditions and a storm is on its way, while rises in pressure mean conditions are more stable and fair weather is returning.

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, fluffy cumulonimbus clouds. Light rain, also known as drizzle, may fall from low, grey, layered cloud called stratus.

Precipitation

SNOW 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 ground. Every snowflake that falls from clouds is different, made from ice crystals and with 6 sides.

Precipitation

HAIL 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

Measuring instruments of weather

Why 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

Temperature

Temperature is measured using a thermometer, with units in degrees on Fahrenheit (ºF) or Celsius (ºC) scales. The main type of thermometer used is the liquid-in-glass thermometer. A liquid (usually alcohol) expands depending on temperature. It then moves up a small tube alongside a scale, from which temperature readings can be made. Thermometers should be put within a Stevenson Screen to stop temperature readings being affected by direct sunlight.

Wind

Wind 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. Another way to find out wind direction is by using a wind sock which you may have seen at airports or airfields.

Wind

Wind 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.

CloudCloud can be measured through a number of observations. 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, and Cumulonimbus

CloudAltitude Name Color Descript

ionWeather

HighCirrus White

Thin silky and

featheryFair

High Cirrocumulus

WhiteRipples/bumps

Fair

HighCirrostratu

sWhitish

Fat, smooth

transparent sheet

Worsening

Medium

Altocumulus

White/grey

Layers and waves

often separated

by blue sky

Fair

MediumAltostratus Grayish

Thin sheets/lay

ers

Rain on way

Medium Nimbostratus

Dark greyThick

sheets

Continuous

rain/snow

CloudAltitude Name Color Descrip

tionWeather

LowStratocumulus

Grey/white

Layers in rounded rolls. No breaks.

Dry/dull

LowStratus Grey

Thin sheet

blanketing sky

Drizzle

Low CumulusGrey/white

Puffy clouds

Good

LowCumulon

imbusGrey/white

Very tall puffy

clouds

Storms. Heavy

rain/hail/snow

Cloud The cloud types above are the most common in the UK,

though more unusual clouds may sometimes be seen. In May 2004, mammoths cloud was visible at the base of a cumulonimbus formation over Broad Oak Nature Reserve.

The amount of cloud in the sky is measured in eighths (or okras by meteorologists). Simple observation can be made such as Clear - no cloud coverPartly cloudy - less than half cloud cover Mainly cloudy - more than half cloud cover but with some breaks in the cloud Overcast - complete cloud cover

Sunshine Hours of sunshine are usually

recorded on a simple machine called a pyrheliometer. also known as a Campbell-Stokes recorder. It works by using a glass ball to focus the sunlight and rays onto a strip of card. As the sun moves round during the day, the card is scorched creating a record of how many sunshine hours there were.

Visibility Visibility can be estimated using descriptive words such as:

good, poor, foggy etc. How far you can see is also used to describe visibility:Fog – less than 1kmPoor – 1 to 5kmModerate – 5 to 10kmGood – more than 10km

Different environments around the world experience different levels of fog. People living high in the mountains may see fog all year. The city of San Francisco in North America is famous for its thick mist that moves in from the Pacific Ocean. In the United Kingdom we mainly see fog in autumn and winter, but some tropical parts of the world may never have seen fog.

There are two types of fog. Click to find out more:1. Advection Fog 2. Radiation Fog

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.

Humidity Relative humidity is a measure of how much

water vapour is actually in the air compared to how much water vapour the air could hold. This is measured using a wet and dry hygrometer. This type of thermometer has two bulbs; one is kept wet in distilled water and the other dry. The difference in temperature between them can be calculated to give relative humidity. Humidity must be high for fog or clouds to form.

Pressure Atmospheric pressure is

measured with a barometer, which can be kept indoors.

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 make comparisons with previous years.

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.

Measuring instruments of weather

So, these are the different types of Measuring instruments of weather that I explained you about. Hope you enjoyed the ppt as much as I enjoyed making it.

Thank You

Made By Aakriti Gupta