Atmosphere and weather


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Atmosphere and weather

  1. 1. •Our earth is surrounded by a blanket of air known as the atmosphere. The atmosphere is made up of a mixture of gases. If compared to the diameter of the Earth, the atmosphere is very thin. •Our atmosphere can be divided into five layers. They are held to the Earth by the force of gravity. There is no actual visible borders between the layers of air and no drastic changes from a layer to the next layer. Instead, the change is gradual
  2. 2. •We live in the troposphere, the layer closest to the ground. It is about 10 km in height and contains 75% of the atmospheric gases. Weather occurs here because this layer contains most of the water vapor. •Above the troposphere lies the stratosphere. The stratosphere extends to the height of 50 km. There is no cloud here and the air is still. Therefore most planes fly in this layer of the air. •The stratosphere contains a thin layer of ozone. This ozone layers absorbs the harmful ultraviolet rays from the Sun. These rays cause sunburn and skin cancer.
  3. 3. •Beyond the stratosphere, the air here is very cold and thin. This layer is known as the mesosphere and it extends to a height of 80 km. most of the meteorites are being slowed down and burnt out in this layer. •The thermosphere is the fourth layer from the ground. It is found between 80 km and 700 km above the Earth. Space shuttles fly in this area. Aurora lights are found here. •The furthest layer of the Earth is the exosphere, where the atmosphere merges into the space. Satellites are stationed here.
  4. 4. •The temperature of the atmosphere varies, depending the height from the Earth. It rises and falls throughout the layers of the atmosphere.
  5. 5. •Weather refers to the present state of the atmosphere. It could be sunny or cloudy, windy or still, wet or dry. •A complete description of weather includes type of clouds, measurement of temperature, wind speed and direction, rain, snow, thunderstorms and the amount of moisture in the temperature.
  6. 6. •Meteorology is the study of entire atmosphere, including the weather. •A meteorologist is a scientist who studies the causes of the weather conditions and also forecast the weather. He also studies subjects not directly related to weather, such as the composition of the atmosphere, the atmosphere of the other planets, and also the causes of the past and present weather.
  7. 7. •A weather forecast is the prediction about the weather that will be experienced a short period of time in the future, for example for the next day or the next few days. •There are thousands of weather stations around the world. These stations record the information about weather. They have instrument to measure temperature, rainfall, wind speed and direction, air pressure and humidity.
  8. 8. •We are dependent to the weather specially those who work outdoors. Bad or good weather has good or bad impact on public health, agriculture, energy, construction, transportation, tourism, recreation, ecosystems and biodiversity.
  9. 9. When it is raining heavily, it can be unpleasant to go outside, but water is essential to life
  10. 10. •Severe weather events, such as cyclones, tornadoes, flash floods, blizzards, heat waves and droughts can effect human lives and property. •Nowadays, weather radar and satellites are also used to help predict the weather more accurately.
  11. 11. •Weather describes the current conditions such as humidity, air pressure and temperature. •These three factors have great effect on the formation of cloud rain and wind. •Air pressure is also known as atmospheric pressure. Air pressure is the weight of the air above the given point.
  12. 12. •Air pressure is usually measured with a barometer. •Changes in the air pressure bring changes in the weather and make wind blow. •Air usually moves from areas of high pressure to areas of low pressure and the produces wind.
  13. 13. •Humidity is the amount of water vapour in the air. Relative humidity is the amount of water vapour that is currently in the air compared to how much the air can hold at a specific temperature. Relative humidity is measured in percentage with 100 % refers to the saturated air at a specific temperature. •Instruments used to measure relative humidity are called hygrometers.
  14. 14. •The amount of water vapour the air can hold depends on the temperature. •A cooler temperature, the molecules in the air move slower. This slow movements allows the water vapour to join together and condense. •A warmer temperature, the molecules move too fast to join together. •Therefore, cooler air holds less water vapour and has a lower humidity.
  15. 15. •The graph below shows the maximum of water vapour in the air at various temperature.
  16. 16. •As the air is heated up, it expands. Therefore, the atmospheric pressure is lowered. •So, the temperature is inversely proportional to atmospheric pressure. When the temperature is high, the atmospheric pressure is lower and vice versa.
  17. 17. •Monsoons, tropical cyclones and thunderstorms are common weather phenomenon in Asia. •A monsoon is a term from early Arabs called the “Mausin” or the season of winds. •This was in reference to the seasonally shifting winds in the Indian Ocean and surrounding regions, including the Arabian Sea.
  18. 18. •There are seasonal changes which are particularly noticed as northeast winds prevailing in the winter in Southeast Asia and southwest winds in the summer. •Monsoons are caused by the fact that land heats up and cool down quicker that water. •Thus, in summer, land reaches a higher temperature that the ocean. The hot air over the land tends to rise, creating an area of low pressure.
  19. 19. •This creates a constant wind blowing toward the land. •As the wind is blown from the sea, a lot of moisture is collected. •So, in Thailand, the southwest monsoon starts in May and ends in September. There is a lot of rain with higher temperatures and humidity.
  20. 20. •In winter, the land cools off quickly, but the oceans retains heat longer. •The hot air over the ocean rises, creating a low pressure area and a wind blowing from land to ocean •As the wind is blown from the land, therefore it contains less moisture. •So, the northeast monsoon starts in October and ends in February with the little rain and lower temperatures and humidity.
  21. 21. •A tropical cyclone (or tropical storm, typhoon, or hurricane, depending on strength and location) is a type of low pressure system which generally forms in the tropics. •Structurally, a tropical cyclone is a large, rotating area of clouds, wind and thunderstorm activity.
  22. 22. •The primary energy source of a tropical cyclone is the release of the heat or condensation from water vapour condensing at high altitudes. Because of this, a tropical cyclone can be thought of as a giant vertical heat engine. •A cyclone has a low air pressure area at its surface and a high air pressure area on top. •Cyclones cause thunderstorms, high winds and flooding.
  23. 23. •Tropical cyclones play an important role in the atmosphere circulation system. They transfer heat from equatorial regions to areas of higher latitudes. •A thunderstorm or T-Storm, is a form of weather characterized by the presence of lightning and its attendant thunder. •It is often accompanied by copious rainfall, hail, or on occasion, snowfall (which is known as thunder snow)
  24. 24. •Thunderstorm forms when significant condensation, resulting in the production of a wide range of water droplets and ice crystals, occurs in atmosphere that is unstable and supports deep, rapid upward motion. •In Thailand thunderstorms are common all throughout the year specially during the southwest monsoon.
  25. 25. •Mild thunderstorms do not cause much damage and only slightly affect us. We may have to postpone a game of a football or seek shelter inside a building.
  26. 26. •Severe thunderstorms and cyclones however are damaging. a.Flash flood commonly occur during thunderstorms. These floods can cause loss of human or animal life and damage crops and property. In the cities, motorists may be stranded in traffic jams that last for hours. b.Winds can easily reach 80 km/h. in severe storms, wind velocity is even higher, reaching more than 90 km/h. such strong winds are dangerous and cause a lot of damage.
  27. 27. c. Thunderstorm may produce hailstones which can damage property and crops and injure human and animals. d. The lightning generated is dangerous too. Lightning may cause loss of lives and property damage. Lightning can also start fires. •If your area is low lying or prone to flooding, have sandbags or other barriers ready to prevent flood waters from entering.
  28. 28. We already learnt that weather phenomenon is dangerous. Let us learn how we can protect ourselves and our property from dangerous weather phenomena. •During storms avoid being out in open fields or open areas. Always seek shelter inside buildings immediately.
  29. 29. •Be familiar with the locations of big drains to avoid falling into them. •Do not drive or operate vehicles. •Move people and furniture to higher levels. •Install good surge protectors and lightning conductors in buildings. Test them frequently to ensure they work.
  30. 30. •Avoid water – based activities such as swimming, fishing or boating. •Do not use machinery such as tractors on farms, road or building construction sites. •Do not play golf. •Do not use the telephone, computer or devices connected to modems.
  31. 31. •Do not repair electrical appliances. •Stay away from windows. •Stay away from electrical power transmission lines. •Move vehicles, outdoor furniture and other such items indoors.
  32. 32. •If your area is low lying or prone to flooding, have sandbags or other barriers ready to prevent floodwaters from entering. •Be familiar with the locations of big drains to avoid falling in them. •Do not drive or operate vehicles. •Move people of furniture to higher levels. •Install good surge protectors and lightning conductors in buildings. Test them frequently to ensure they work.
  33. 33. •Weather forecasting is the science of predicting the state of the atmosphere for a future time and location. •The history of weather forecasting goes back millennia, however the techniques used have changed significantly since then.
  34. 34. •Today, weather forecasts are made by collecting as much data as possible about the current state of the atmosphere and using understanding of atmospheric processes to determine how the atmosphere evolves in the future. •However, the chaotic nature of the atmosphere and incomplete understanding of the processes mean that forecasts become less accurate as the range of the forecast increases.
  35. 35. •A weather forecasts predicts what the weather in the future is likely to be. •Information from the meteorologists and satellites are analyzed, using computers, and a station model is produced. •A station model shows the weather condition at a specific location using symbols.
  36. 36. •In addition to the station model, weather map has lines that indicate the atmospheric pressure and temperature. •An isobar is drawn to connect points of equal atmospheric pressure. •Weather forecasts are important because severe weather phenomenon is dangerous.
  37. 37. •When we study weather forecasts, we can be warned dangerous weather phenomenon and take the necessary precautions to avoid loss of life and property damage. •Certain economic activities, for example fishing and agriculture are very dependent on the weather conditions. Accurate and reliable weather forecasts are even more important in these fields.