Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download What are climatic elements? What are their distribution
Document related concepts
no text concepts found
Transcript
Part 9 9.2 Weather and climate What are climatic elements? What are their distribution patterns? Part B © Oxford University Press 2010 Quit Part 9 Weather and climate What are condensation and precipitation? Why does it rain? How does water change in state? Let's start with the water vapour in the air! © Oxford University Press 2010 Quit Part 9 Weather and climate What are condensation and precipitation? Water vapour and relative humidity Air holds a certain amount of water vapour. How are the maximum amount of water vapour that air can hold and temperature related? The maximum amount of water vapour that air can hold ( decreases / increases ) with increasing temperature. © Oxford University Press 2010 Quit Part 9 Weather and climate Water vapour and relative humidity Air However, the air does not always hold the maximum amount of water. In what way can we know how humid the air is? By calculating the relative humidity. © Oxford University Press 2010 Quit Part 9 Weather and climate Water vapour and relative humidity Relative humidity = Actual amount of vapour in air What is the maximum capacity of water vapour that air can hold at 23ºC? × 100% Maximum amount of vapour at a fixed temperature Example Air temperature: 23ºC 20g/m3. Actual amount of water vapour in the air: 10 g/m3 Relative humidity = 10g/m3 20g/m3 © Oxford University Press 2010 × 100% = 50% Quit Part 9 Weather and climate Water vapour and relative humidity How does relative humidity change when temperature changes? The actual amount of water vapour in the air remains unchanged (10 g/m3). When the temperature is 20ºC, the maximum capacity of water vapour that air can hold is _____ 16 g/m3. Relative humidity = With the same amount of water 3 10g/m vapour, the lower the temperature, = 62.5% × 100% the higher 16g/m3the relative humidity. © Oxford University Press 2010 Quit Part 9 Weather and climate Saturation and condensation What happens when the relative humidity reaches 100%? When the relative humidity reaches 100%, the amount of water vapour in the air is at its __________ maximum capacity. The air reaches a state called ___________. saturation The temperature at which saturation occurs is known as the ___________. dew point © Oxford University Press 2010 Quit Part 9 Weather and climate Saturation and condensation What is the dew point if an air parcel holds 28g/m3 of moisture? © Oxford University Press 2010 Quit Part 9 Weather and climate Saturation and condensation Water vapour Water vapour Water vapour What happens when the air is saturated? Water vapour The excess vapour Condensation will gather on tiny Water droplet nucleus Water particles in the air and vapour Water form droplets. They vapour Water are known as vapour Water Water condensation nuclei. vapour vapour Condensation occurs when there is excess water vapour. The level at which condensation occurs is known as the _____________ condensation level. Water vapour © Oxford University Press 2010 Quit Part 9 Weather and climate (Credit: Liang Wing Hang Yanchap) Saturation and condensation High level Above the ground/ over the sea Clouds We can find different Ground forms oflevel condensation at different levels. FogThe condensation level varies in different places. Dew © Oxford University Press 2010 Frost Quit Part 9 Weather and climate Precipitation What happens to the water droplets when they become too heavy for the uprising air to support? Water droplets fall to the ground. Precipitation is the falling of water in ( solid / liquid / gaseous ) form from clouds. © Oxford University Press 2010 Quit Part 9 Weather and climate What types of rain are there? Rain can be classified into three types according to the causes for air to rise. Relief rain Types of rain Convection rain Frontal rain © Oxford University Press 2010 Quit Part 9 Weather and climate What is the world distribution pattern of rainfall? No, it is unevenly Annual rainfall distribution Polar areas Areas near 60ºN distributed. Some areas receive more rainfall annually. Areas near 30ºN Equatorial area Is annual rainfall Areas near 30ºS evenly distributed throughout the world? Areas near 60ºS Polar areas © Oxford University Press 2010 World distribution of annual rainfall Quit Part 9 Weather and climate What is the world distribution pattern of rainfall? Annual rainfall distribution Onshore westerlies bring rainfall. East and west coasts at the same latitude receive High-latitude regions different amount of C D rainfall. Less More rainfall rainfall Low-latitude regions A Less rainfall B More rainfall Onshore trade winds rainfall. Dobring areas at the same latitude receive the same amount of rainfall? World distribution of annual rainfall © Oxford University Press 2010 Quit Part 9 Weather and climate Seasonal distribution of rainfall Some regions have a seasonal pattern of rainfall. World distribution of annual rainfall © Oxford University Press 2010 Quit Part 9 Weather and climate What factors affect the world distribution of rainfall? Air pressure ( does not affect / 1 Air pressure Air temperature is high at you/ high- ) ( low- Can / midconclude the latitude regions relationship between air Highpressure temperature andresults inthe lowglobal pressure distribution of rainfall? Low-latitude regions receive more rainfall under low pressure © Oxford University Press 2010 affects ) the global distribution of rainfall. Low-pressure areas have ( less / more ) rain than highpressure areas. Condensation Why? Low-pressure area Quit Part 9 Weather and climate What factors affect the world distribution of rainfall? Air pressure Apart from air pressure, what other factors will affect the world distribution of rainfall? Winds Distance from the sea Ocean currents Relief © Oxford University Press 2010 Quit Part 9 Weather and climate What is the inter-relationship between insolation and the climatic elements? Insolation Affects Air temperature Affects Affects Affects Precipitation Air pressure Affects Wind © Oxford University Press 2010 Affects Quit Part 9 © Oxford University Press 2010 Weather and climate Quit Part 9 © Oxford University Press 2010 Weather and climate Quit Part 9 1 Weather and climate Relief rain _______ Relief is the most important factor in causing relief rain. Relief rain occurs on the ( windward / leeward ) slope of the mountain. Please click above for animation © Oxford University Press 2010 Quit Part 9 2 Weather and climate Convection rain Condensation level What happens when What happens What happens to the air What happens to the What happens as saturated air reach when the ground is when the air relative humidity when the condensation airintensely continue to rise? heated? temperature falls? continues to rise? level? Strong convection Air cools down currents help the Water vapour development of thick condenses clouds into clouds Water is saturated in the air Cooler air Relative humidityrain Convection sinks to increases Air temperature fallsreplace the Air expands rising air and rises IntenselyEarth’s heatedsurface earth’s surface © Oxford University Press 2010 Quit Part 9 2 Weather and climate Convection rain Convection rain commonly occurs in __________ tropical regions and ___________________ continental interiors during summer. In Hong Kong, convection rain mainly occurs in _________ summer when the land is intensely heated. © Oxford University Press 2010 Quit Part 9 2 Weather and climate Convection rain Convection rain usually occurs in the __________ afternoon (time of a day), when the ___________ convection current is the strongest. The duration of rain is ( short / long ). Convection rain is often accompanied by ________________. thunderstorms © Oxford University Press 2010 Quit Part 9 Weather and climate 3 Frontal rain How do these two kinds Which What will kindbeofformed air is of air Warm move when air. they after lighter the and air less is saturated? dense? meet? A front is where warm air and cold air meet. Water vapour condenses into clouds Condensation level Air becomes saturated Frontal rain Warm air rises along the front Warm air Air cools down Cold air Cold air remains close to the ground Earth’s surface © Oxford University Press 2010 Quit Part 9 3 Weather and climate Frontal rain At which regions do frontal rain frequently occur? Cold air from the polar high Front Warm air rises along the front North Pole Polar high 60ºN Subpolar low Warm air from the subtropical high 30ºN Frontal rain frequently occurs at around _____ºN and S. 60 © Oxford University Press 2010 0º Subtropical high Equatorial Low Quit Part 9 3 Weather and climate Frontal rain If air rises rapidly, ( light rain / heavy showers ) will accompany with _______________. thunderstorms If air rises slowly, the rain will be light and steady. © Oxford University Press 2010 Quit Part 9 Weather and climate Equatorial area In which pressure belt is the equatorial area located? Equatorial area has an annual rainfall of over ________ 1,000 mm. It is located in the ________________. equatorial low © Oxford University Press 2010 Quit Part 9 Weather and climate Equatorial area Why is annual rainfall high here? ___________ rainlow, forms strong heating. In the equatorial NEfrom and SE ___________ trade winds converge. Convection Air ( sinks / rises ) and forms rainfall. High temperature and abundant _________ ______ moisture in the air favour rainfall. © Oxford University Press 2010 Quit Part 9 Weather and climate Areas near 30ºN and S In which pressure belt are these areas located? Most places near 30ºN and S have an annual rainfall of below _______ 500 mm. subtropical highs These areas are located in the _________________. © Oxford University Press 2010 Quit Part 9 Weather and climate North Pole Polar high Areas near 30ºN and S In subtropical highs, air ( sinks / rises ) throughout the year. 60ºN Subpolar low Subtropical high 30ºN The sinking air brings ( dry / wet ) climate to these areas. Equatorial Low 0º Subtropical high 30ºS 60ºS Subpolar low Polar high South Pole © Oxford University Press 2010 Quit Part 9 Weather and climate Areas near 60ºN and S Which pressure belt is found at around 60ºN and S? These areas receive an annual rainfall between 250 mm and 1,000 mm. Cold polar lows air meets warm ___________. Air60˚S. rises and ______________ are located near 60˚N and Subpolar westerlies forms _________ frontal rain. © Oxford University Press 2010 Quit Part 9 Weather and climate North Pole Polar areas In which pressure belts are polar areas located? Polar areas are located in the polar highs _____________. Polar high 60ºN Subpolar low Subtropical high 30ºN Equatorial Low 0º These areas have an annual rainfall of below 250 mm. In polar highs, cold air ( sinks / rises ) throughout the year. The sinking air does not favour the formation of rain. © Oxford University Press 2010 Subtropical high 30ºS 60ºS Subpolar low Polar high South Pole Quit Part 9 Weather and climate Winds Onshore winds are ( dry / wet ), while offshore winds are ( dry / wet ). ( Onshore / Offshore ) winds bring rainfall. © Oxford University Press 2010 Do you remember the nature of onshore and offshore winds? Quit Part 9 Weather and climate Distance from the sea The onshore winds keep losing moisture through _____________ precipitation as they move inland. Onshore winds Rainfall ( decreases / increases ) with increasing distance from the sea. The continental interior is ( drier / wetter ) than the coastal areas. © Oxford University Press 2010 Quit Part 9 Weather and climate Ocean currents Warm currents contain more _________. moisture Winds blowing over a warm current bring ( little / much ) rainfall to the coast. © Oxford University Press 2010 Cold currents contain less moisture. Winds passing over a cold current bring little rainfall to the coast. Quit Part 9 Relief © Oxford University Press 2010 Weather and climate Which side of the mountain receives higher rainfall? Quit
