494 thoughts on “Chennai opens its NEM account

  1. Preliminary Rainfall in and around Chennai Region

    in mm ending 8.30 am on 01.10.2013

    Korattur Anicut – 15
    Meenambakkam – 12
    Chembarabakkam Lake – 10
    Katupakkam – 9
    Poonamalle – 7
    Poondi Lake – 6
    Avadi – 5
    Tiruvallur – 5
    Taramani – 5
    Vellore – 5
    Redhills – 3
    Guindy – 3
    Puzhal – 3
    Katpadi – 3
    Madhavaram – 3
    Nungambakkam – 2

  2. The chief amounts of rainfall (2
    cm or more) recorded at 1730 hours IST of yesterday were: 

    Dharamshala­6; Barmer­5; Bhira and Jagdalpur­4
    each; Cannur and Agumbe­3 each and Meerut, 
    Baharampur, Cherrapunji, Bhubaneshwar and 
    Chandbali­2 each.

  3. The   upper air cyclonic circulation over southeast Rajasthan & 
    neighbourhood extending upto 3.6 Km
    above mean sea level persists

  4. The low pressure area over northwest Bay of Bengal and 
    neighbourhood persists with associated upper
    air cyclonic circulation extending upto mid­tropospheric levels.

  5. Odisha Rains

    Stations MM
    KORAPUT 49
    KHURDAH 38
    PURI 33

  6. Rain in West Bengal in MM

    KOLKATA 59
    CANNING 40
    TAMLUK 35
    SURI 16
    BURDWAN 10

  7. Melting Arctic Permafrost Looms as Major Factor in Warming, Climate Change

    Permafrost, which is frozen ground that doesn‚Äôt melt during the summer, covers 24 percent of the land in the northern hemisphere. It also stores approximately 1.5 trillion tons of carbon ‚Äď twice the amount of carbon currently in the atmosphere.

    Read more at http://www.wunderground.com/news/melting-arctic-permafrost-looms-major-factor-warming-climate-change-20130927#lEXD3UZ2QXRpa9Su.99

  8. The clouds seem to speak

    Description: As the anniversary of the September 11, 2001 terrorist attack approaches, a test of the Tribute in Light Memorial illuminates a passing cloud above lower Manhattan. The twin towers of light, made-up of 44 searchlights near Ground Zero, are meant to represent the fallen twin towers of the World Trade Center. Depending on weather conditions, the columns of light can be seen for at least 20 miles around the trade center complex. U.S. Coast Guard

  9. Anticyclone
    An anticyclone is a region of high atmospheric pressure relative to the surrounding air, generally thousands of kilometres in diameter and also known as a high or high-pressure system. Anticyclones appear on weather charts as a series of concentric, widely spaced isobars of 1000 mbs and above. The roughly circular closed isobar at its central region indicates the area of highest pressure.

    More on this :http://www.weatheronline.in/reports/wxfacts/Anticyclone.htm

  10. Bubble High

    Bubble High Thunderstorms develop as warm, moist air rises turning into rain or hail. As the thunderstorm reaches its mature stage, violent updrafts are noted and precipitation begins. At the onset of precipitation, strong downdrafts develop. Falling precipitation reverses rising air columns by frictional drag and cooling, and the storm eventually begins to dissipate or collapse.

    For More info :http://www.weatheronline.in/reports/wxfacts/Bubble-High.htm

  11. Cloud seeding

    Cloud seeding Cloudseeding is the technique of inducing rain from a cloud, usually by dropping suitable particles into clouds containing supercooled water in an attempt to cause them to dissipate, modify their structure, or alter the intensity of associated phenomena, such as wind speed or hail.

    Natural rainfall occurs when supercooled cold water contacts particles of dust, salt or sand forming ice crystals. The ice crystals provide a nucleus (tiny solid or liquid particles, suspended in the atmosphere) around which more water droplets can attach, increasing the size of the droplet, or in colder air snow flakes. When the droplet or snow flake, becomes large enough, it falls as snow or rain.

    More info at http://www.weatheronline.in/reports/wxfacts/Cloud-seeding.htm

  12. What is dBZ used in RADAR ?

    Nondimensional “unit” of radar reflectivity which represents a logarithmic power ratio (in decibels, or dB) with respect to radar reflectivity factor, Z.

  13. Divergence
    The expansion or spreading out of a vector field; usually said of horizontal winds. It is the opposite of convergence. Divergence at upper levels of the atmosphere enhances upward motion, and hence the potential for thunderstorm development (if other factors also are favorable).

    • Convergence
      A contraction of a vector field; the opposite of divergence. Convergence in a horizontal wind field indicates that more air is entering a given area than is leaving at that level. To compensate for the resulting “excess,” vertical motion may result: upward forcing if convergence is at low levels, or downward forcing (subsidence) if convergence is at high levels. Upward forcing from low-level convergence increases the potential for thunderstorm development (when other factors, such as instability, are favorable). Compare with confluence.

  14. Dew Point Depression
    The difference in degrees between the air temperature and the dew point.

    Dew Point Front
    A narrow zone (mesoscale feature) of extremely sharp moisture gradient and little temperature gradient. It separates moist air from dry air. Severe weather can be associated with this front. It is also known as a “dryline” or “dry front”.

    On a buoy report, the dewpoint temperature taken at the same height as the air temperature measurement.

  15. Climatology
    The science that deals with the phenomena of climates or climatic conditions.

    An instrument that measures angles of inclination; used to measure cloud ceiling heights.

    • Convection
      Generally, transport of heat and moisture by the movement of a fluid.

      In meteorology, the term is used specifically to describe vertical transport of heat and moisture in the atmosphere, especially by updrafts and downdrafts in an unstable atmosphere. The terms “convection” and “thunderstorms” often are used interchangeably, although thunderstorms are only one form of convection. Cbs, towering cumulus clouds, and ACCAS clouds all are visible forms of convection. However, convection is not always made visible by clouds. Convection which occurs without cloud formation is called dry convection, while the visible convection processes referred to above are forms of moist convection.

  16. Convective Clouds
    The vertically developed family of clouds are cumulus and cumulonimbus. The height of their bases range from as low as 1,000 feet to a bit more than 10,000 feet. Clouds with extensive vertical development are positive indications of unstable air. Strong upward currents in vertically developed clouds can carry high concentrations of supercooled water to high levels where temperatures are quite cold. Upper portions of these clouds may be composed of water and ice.

    • Shear
      Variation in wind speed (speed shear) and/or direction (directional shear) over a short distance within the atmosphere. Shear usually refers to vertical wind shear, i.e., the change in wind with height, but the term also is used in Doppler radar to describe changes in radial velocity over short horizontal distances.

    • Shelf Cloud
      A low, horizontal wedge-shaped arcus cloud, associated with a thunderstorm gust front (or occasionally with a cold front, even in the absence of thunderstorms). Unlike the roll cloud, the shelf cloud is attached to the base of the parent cloud above it (usually a thunderstorm). Rising cloud motion often can be seen in the leading (outer) part of the shelf cloud, while the underside often appears turbulent, boiling, and wind-torn.

    • Rame… info like this is actually a sight for sore eyes in the blog… Pretty much all your posts today has actually been informative and interesting compared to the bulletins and imd info which gets copy pasted here! Good Job Rame!

  17. Sky Condition
    Used in a forecast to describes the predominant/average sky condition based upon octants (eighths) of the sky covered by opaque (not transparent) clouds.

    Sky Condition Cloud Coverage
    Clear / Sunny 0/8
    Mostly Clear / Mostly Sunny 1/8 to 2/8
    Partly Cloudy / Partly Sunny 3/8 to 4/8
    Mostly Cloudy / Considerable Cloudiness 5/8 to 7/8
    Cloudy 8/8
    Fair (mainly for night) Less than 4/10 opaque clouds, no precipitation, no extremes of

  18. Squall
    A strong wind characterized by a sudden onset in which the wind speed increases at least 16 knots and is sustained at 22 knots or more for at least one minute. 2. In nautical use, a severe local storm considered as a whole, that is, winds and cloud mass and (if any) precipitation, thunder and lightning.

    Squall Line
    A line of active thunderstorms, either continuous or with breaks, including contiguous precipitation areas resulting from the existence of the thunderstorms.

    • Supercell
      Short reference to Supercell Thunderstorm; potentially the most dangerous of the convective storm types. Storms possessing this structure have been observed to generate the vast majority of long-lived strong and violent (F2-F5) tornadoes, as well as downburst damage and large hail. It is defined as a thunderstorm consisting of one quasi-steady to rotating updraft which may exist for several hours.

      • Supercell Thunderstorm
        Potentially the most dangerous of the convective storm types. Storms possessing this structure have been observed to generate the vast majority of long-lived strong and violent (F2-F5) tornadoes, as well as downburst damage and large hail. It is defined as a thunderstorm consisting of one quasi-steady to rotating updraft which may exist for several hours. Supercells usually move to the right of the mean wind. These are called “Right Movers” and they are favored with veering winds. Occasionally, these thunderstorms will move to the left of the mean wind. These thunderstorms are called “Left Movers”. These supercells typically don’t last as long as their “Right Mover” cousins and they usually only produce large hail (greater than 3/4 inch in diameter) and severe wind gusts in the excess of 58 miles an hour. Left Movers are favored when you have backing winds.

        Radar will observe essentially one long-lived cell, but small perturbations to the cell structure may be evident. The stronger the updraft, the better the chance that the supercell will produce severe (hail greater than 3/4 inch in diameter, wind gusts greater than 58 miles an hour, and possibly a tornado) weather.

        Severe supercell development is most likely in an environment possessing great buoyancy (CAPE) and large vertical wind shear. A Bulk Richardson Number of between 15 and 35 favor supercell development. Typically, the hodograph will look like a horse shoe. This is due to the wind speed increasing rapidly with height and the wind direction either veering or backing rapidly with height.

    • KT
      (Knot)- Unit of speed used in navigation, equal to 1 nautical mile (the length of 1 minute latitude) per hour or about 1.15 statue miles per hour, or 0.5 meters/sec).


  19. Let’s hope that whatever is gonna strike WB/Orissa should not go past tropical storm intensity. Tropical storms are fine, but if it becomes severe, chances of a good NEM will end even before the NEM starts ūüėź

  20. Sea Breeze Front
    The leading edge of a sea breeze, whose passage is often accompanied by showers, a wind shift, or a sudden drop in temperature.

    Sea Level Pressure
    The sea level pressure is the atmospheric pressure at sea level at a given location. When observed at a reporting station that is not at sea level (nearly all stations), it is a correction of the station pressure to sea level. This correction takes into account the standard variation of pressure with height and the influence of temperature variations with height on the pressure. The temperature used in the sea level correction is a twelve hour mean, eliminating diurnal effects. Once calculated, horizontal variations of sea level pressure may be compared for location of high and low pressure areas and fronts.

    Sea Surface Temperatures
    The term refers to the mean temperature of the ocean in the upper few meters.

  21. Barogram
    An analog record of pressure produced by a barograph
    A barometer that records its observations continuously.
    An instrument that measures atmospheric pressure.
    Barometric Pressure
    The pressure of the atmosphere as indicated by a barometer.

  22. Important term used in Doppler Radar

    Base Reflectivity
    One of the three fundamental quantities (along with base [radial] velocity and spectrum width) that a Doppler radar measures. Reflectivity is related to the power, or intensity, of the reflected radiation that is sensed by the radar antenna. Base reflectivity is expressed on a logarithmic scale in units called dBZ. The term “base” refers to the product being “basic”, with little advanced processing performed on the data. Base reflectivity is related to rainfall intensity (e.g., drop size and rainfall rate) and hail size (for large values of reflectivity).

  23. Beaufort Scale
    The Beaufort wind scale is a system used to estimate and report wind speeds when no measuring apparatus is available. It was invented in the early 19th Century by Admiral Sir Francis Beaufort of the British Navy as a way to interpret winds from conditions at sea. Since that time, the scale has been modernized for effects on land.

    • Beaufort Force 0 – Wind less than 1 kt, Calm, Sea surface smooth and mirror-like. Smoke rises vertically.

      Beaufort Force 1 – Wind 1-3 kt, Light Air, Scaly ripples, no foam crests. Smoke drift indicates wind direction, still wind vanes.

      Beaufort Force 2 – Wind 4-6 kt, Light Breeze, Small wavelets, crests glassy, no breaking waves. Wind felt on face, leaves rustle, vanes begin to move.

      Beaufort Force 3 – Wind 7-10 kt, Gentle Breeze, Large wavelets, crests begin to break, scattered whitecaps. Leaves and small twigs constantly moving, light flags extended.

    • Beaufort Force 4 – Winds 11-16 kt, Moderate Breeze, Small waves 1 -4 ft. becoming longer, numerous whitecaps. Dust, leaves, and loose paper lifted, small tree branches move.

      Beaufort Force 5 – Winds 17-21 kt, Fresh Breeze, Moderate waves 4 -8 ft taking longer form, many whitecaps, some spray. Small trees in leaf begin to sway.

      Beaufort Force 6 – Winds 22-27 kt, Strong Breeze, Larger waves 8 -13 ft, whitecaps common, more spray. Larger tree branches moving, whistling in wires.

      Beaufort Force 7 – Winds 28-33 kt, Near Gale, Sea heaps up, waves 13 -20 ft, white foam streaks off breakers. Whole trees moving, resistance felt walking against wind.

    • Beaufort Force 8 – Winds 34-40 kt Gale, Moderately high (13 -20 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks. Whole trees in motion, resistance felt walking against wind.

      Beaufort Force 9 – Winds 41-47 kt, Strong Gale, High waves (20 ft), sea begins to roll, dense streaks of foam, spray may reduce visibility. Slight structural damage occurs, slate blows off roofs.

      Beaufort Force 10 – Winds 48-55 kt, Storm, Very high waves (20 -30 ft) with overhanging crests, sea white densely blown foam, heavy rolling, lowered visibility. Seldom experienced on land, trees broken or uprooted, “considerable structural damage”.

    • Beaufort Force 11 – Winds 56-63 kt, Violent Storm, Exceptionally high (30 -45 ft) waves, foam patches cover sea, visibility more reduced.

      Beaufort Force 12 -Winds 64+ kt, Hurricane, Air filled with foam, waves over 45 ft, sea completely white with driving spray, visibility greatly reduced.

  24. @Partha

    You sure about south bay ?? Then we’ll have a spell similar to what we got this August. btw, i got to go out now.

  25. Rain in MM in odisha

    BALASORE 194.7
    SONEPUR 89
    CHANDBALI 82.1
    BARIPADA 54.2
    KORAPUT 50.8
    BOLANGIR 30.6
    PURI 16.2
    GOPALPUR 13.8
    SAMBALPUR 12.4
    TALCHER 10
    PARADIP 8.4
    ANGUL 7.6
    CUTTACK 2.4
    HIRAKUD 0.4

  26. Blizzard
    (abbrev. BLZD)- A blizzard means that the following conditions are expected to prevail for a period of 3 hours or longer:
    Sustained wind or frequent gusts to 35 miles an hour or greater; and
    Considerable falling and/or blowing snow (i.e., reducing visibility frequently to less than ¬ľ mile)


    Hail Size
    Typically refers to the diameter of the hailstones. Warnings and reports may report hail size through comparisons with real-world objects that correspond to certain diameters:

    Description | Diameter (inches)
    Pea | 0.25
    Marble or Mothball | 0.50
    Penny or Dime | 0.75
    Nickel | 0.88
    Quarter | 1.00
    Half Dollar | 1.25
    Walnut or Ping Pong Ball | 1.50
    Golfball | 1.75
    Hen’s Egg | 2.00
    Tennis Ball | 2.50
    Baseball | 2.75
    Tea Cup | 3.00
    Grapefruit | 4.00
    Softball | 4.50

  28. RADAR
    Acronym for RAdio Detection And Ranging; a radio device or system for locating an object by means of ultrahigh-frequency radio waves reflected from the object and received, observed, and analyzed by the receiving part of the device in such a way that characteristics (as distance and direction) of the object may be determined.

    • Radar Range
      Distance from the radar antenna. The WSR-88D radar has a range for velocity products out to 124 nautical miles and reflectivity products out to 248 nautical miles.

      Radar Reflectivity
      The sum of all backscattering cross-sections (e.g., precipitation particles) in a pulse resolution volume divided by that volume. The radar reflectivity can be related to the radar reflectivity factor through the dielectric constant term |K|^2, and the radar wavelength.

      Radar Reflectivity Factor (z)
      z = the sum (over i) of (N_i * D_i^6), where N_i is the number of drops of diameter D_i in a pulse resolution volume. Note that z may be expressed in linear or logarithmic units. The radar reflectivity factor is simply a more meteorologically meaningful way of expressing the radar reflectivity.

  29. Those logging in today are virtually assured of understanding the various complex weather terminologies commonly discussed by weather experts..Though these terms and terminologies are readily available in various weather related web pages,it becomes imperative for us to go through and refresh ourselves time and again..Keeping this in mind,RameshSquall has been posting some important notes on the terminologies used..Informative to all and sundry,,Kea can have a separate page on weather terminologies commonly used for easy reference..Bloggers would benefit a lot..This could be added to Data pages of Pradeep, Kar etc.. Good job Rame…Ensure the posts are not lengthy ones..That’s it..

  30. Relative Humidity
    A dimensionless ratio, expressed in percent, of the amount of atmospheric moisture present relative to the amount that would be present if the air were saturated. Since the latter amount is dependent on temperature, relative humidity is a function of both moisture content and temperature. As such, relative humidity by itself does not directly indicate the actual amount of atmospheric moisture present. See dew point.

    Relative Vorticity
    The sum of the rotation of an air parcel about the axis of the pressure system and the rotation of the parcel about its own axis.

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