Structure of atmosphere MeteorologicalEnvironmental parameters Meteorological phenomena Scopes

Structure of atmosphere Meteorological/Environmental parameters Meteorological phenomena

Scopes of studies Climatology and Meteorology are branches of similar areas of study. Climatology is focused on averages of weather and climatic conditions over a long period of time. Meteorology focuses more on current weather conditions such as humidity, air pressure, and temperatures and forecasting the short-term weather conditions to come.

http: //en. wikipedia. org/wiki/Earth's_atmosphere Ozone maximum

Refer to: 1. Layers of the Atmosphere (National Weather Service Jet. Stream – Online School for Weather, www. srh. noaa. gov/srh/jetstream/atmos/layers. htm) 2. E. Aguado and J. E. Burt, Chapter 1 of Understanding Weather and Climate

Troposphere 對流層 • The troposphere ranges form the earth surface to 8 -16 km (mean 11 km) height. • We are living in this region, even travelling in a plane. • Almost all weather occurs in this region. • Air concentration drops with height. • Temperature drops with height from 17°C (62°F) to -51°C (60°F), because air is mainly warmed by radiation from the surface. • Decreasing temperature with height causes convection of air. • The upper transition boundary is called the tropopause.

Stratosphere 同溫層; 平流層 • The stratosphere ranges from 20 – 50 km height. • It holds 19% of the atmosphere's gases but very little water vapor. The temperature increases from -57 to -2 o. C with increasing height. • The upper regions receives more intense UV radiation. More UV is absorbed by oxygen causing a higher temperature. Less UV radiation reaches the lower boundary, where a lower temperature is resulted. • A balance between cooling effect with height and UV heating is reached near the bottom of this layer, resulting in a constant temp range. • Ozone reaches the max. concentration. • The increase of temperature with height results in a calm layer with slow gas movement. • The upper boundary is called the stratopause.

Mesosphere • The mesosphere extends from the stratopause to 85 km above the surface. • It is believed that the absorption of solar radiation at the bottom provides most of the heat of this layer. Heat is dispersed upward by vertical air motion. • On average, temperature decreases from -15°C to 120°C from bottom to top of the layer. • The top boundary is called the mesopause. • The gases in this layer are thick enough to slow down meteorites (流星) hurtling into the atmosphere, where they burn up, leaving fiery trails in the night sky.

Thermosphere • Thermosphere extends from the mesopause to 690 km above the earth. • Higher energy ultraviolet and x-ray radiation from the sun are absorbed by gas molecules which concentrations are very low. • Temperature of the ionized species could be as high as 2000°C. • However, despite the high temperature, this layer is still very cold to our skin because of the extremely thin air.

Earth-atmosphere energy balance Spectra of solar radiation and terrestrial radiation http: //www. stvincent. ac. uk/Resources/Weather/Meteosat/System/imaging. html

Earth-atmosphere energy balance Why is the sky blue (Scattering of light)? http: //www. phys. ufl. edu/~avery/course/3 400/atmosphere? N=A Why are sunsets red (scattering of light)? http: //www. weatherquestions. com/Why_ are_sunsets_red. htm

Earth-Atmosphere energy balance http: //www. srh. noaa. gov/srh/jetstream/atmos/energy_balance. htm A stable temperature is reached. Wind chill effect

http: //atschool. eduweb. co. uk/kingworc/departments/geography/not tingham/atmosphere/pages/solarradiationalevel. html

Causing internal movements of fluid systems (water in ocean and air) to keep a steady state of the globe. Circulation of ocean streams

Atmospheric circulation

“Greenhouse effect”: A greenhouse is designed to admit both long and short wavelength radiation, and is opaque to the re-irradiated long wavelength radiation. It also precludes heat loss due to convection. The latter effect does not exactly occurs in the atmosphere (not a true greenhouse effect). Moreover, if there is no greenhouse effect, the mean temp of the earth would be -18 o. C, and oscillate widely from day to night.

Earth surface temperature distribution North America South America Europe Asia Africa Australia Antarctica

Ice point: 0°C or 32°F (in this case °C = °F – 32) Catching a fever: 40°C or 104°F (°C = (°F-32)x a factor smaller than 1, i. e. 5/9) °C = (°F-32) x 5/9 °F = °Cx 9/5 + 32

Temperature Description Very Cold 嚴 寒 Cold 寒 冷 Cool 清 涼 Temperature (o. C) <= 7 o. C 8 - 12 o. C 13 - 17 o. C Mild 和 暖 Warm 溫 暖 Hot 炎 熱 Very Hot 酷 熱 18 - 22 o. C 23 - 27 o. C 28 - 32 o. C >= 33 o. C

Measurements of temperature Recording the volume change of mercury of alcohol. Disadvantage is not ready for autorecording. Mercury thermometer Alcohol thermometer Measurement range： 10 C - 100 C Range: 30 C - 60 C

Electronic thermometer is needed • • For automatic recording 電腦網絡傳送) For the convenience of data transfer (through internet/wireless technology, recording in computer and server) Remote sensing More accurate Platinum thermometer Radiosonde telemetry

Atmospheric pressure and Wind Pressure = weight of air / area in or or or Pa = N/m² h. Pa = 100 Pa atm (atmospheric pressure) bar 1 standard atmospheric pressure = 1. 013 x 105 Pa = 1013 h. Pa (hectopascal) = 1 bar = 1000 mbar

Barometer (氣壓計) In Barometer, there is a pressure sensor: Pressure changes electrical capacitance

Height dependence of pressure Sea level pressure ~ P(0) = 1000 mb (1 atm) Pressure drops with height (h): P(h) = P(0) e-h/H where H is a constant

http: //gb. weather. gov. hk/education/packag e/pack 01_severe_wx/severewx. html

http: //www. marinewaypoints. com/marine/wind. shtml Beaufort No. Description Wind Speed (km / hr) Effects Land 0 Calm < 2 Still, calm air, smoke will rise vertically. 1 Light Air 2 - Rising smoke drifts, wind vane is inactive. 2 Light Breeze -12 Leaves rustle, can feel wind on your face, wind vanes begin to move. 3 Gentle Breeze 13 - Leaves and small twigs move, light weight flags extend. 4 Moderate Breeze - 30 Small branches move, raises dust, leaves and paper. 5 Fresh Breeze 31 - 40 6 Strong Breeze 41 - Large tree branches move, telephone wires begin to "whistle", umbrellas are difficult to keep under control. 7 Moderate Gale 62 - Large trees sway, becoming difficult to walk. 8 Gale 63 - Twigs and small branches are broken from trees, walking is difficult. 9 Strong Gale - 87 Slight damage occurs to buildings, shingles are blown off of roofs. 10 Storm 88 - Trees are broken or uprooted, building damage is considerable. 11 Violent Storm - 117 Extensive widespread damage. 12 Hurricane 118+ Extreme destruction, devastation. Small trees sway.

Weather Map Wind Symbols (1 knot = 1. 85 km / hr)

Composition of the atmosphere Permanent gases Constituent percentage Nitrogen 78. 08 Oxygen 20. 95 Argon 0. 93 Ne, He, Kr, Xe, H 2 Remainder Variable gases: Though the contents are rare, but is important to meteorological phenomena, and have great influence to comfort. Constituent percentage Water vapor 0. 25 CO 2 0. 038 Ozone 0. 01

Measurement of wind speed and direction wind vane (風向計) wind cup (風杯) anemometer (風速計)

Turbo Meter • A turbine rotates freely at a speed directly proportional to the wind speed. • The resulting signal is processed and displayed.

Relative Humidity Description Very Dry Humid Relative Humidity ( % ) 0 - 40 % 40 - 70 % 85 - 95 % Very Humid 95 - 100 %

Relative humidity Water evaporate Vapor compense water (of sea) (cloud, （Rain, dew） fog) Relative humidity = content of water vapor in air relative to the saturated value

Relative humidity in % = amount of vapor/maximum quantity of water at that temperature Average relative humidity in HK ~ 70 -80% In winter : ~30 -40% When red signal of rainstorm is in force: RH ~ 100%

Rain fall 黃色暴雨警告信號 紅色暴雨警告信號 黑色暴雨警告信號 In broad area of Hong Kong, a rainfall of 30 mm/h is recorded In broad area of Hong Kong, a rainfall of 50 mm/h is recorded In broad area of Hong Kong, a rainfall of 70 mm/h is recorded

Rain gauge : as simple as a cylindrical container + a ruler

Make your own rain gauge http: //www. fi. edu/weather/todo/r-gauge. html

With two flip-flop buckets, each with a conducting contact for counting the time of switching cycles. Rainfall (in mm/hr) = volume / area of the entrance / time of measurement