Sökning: "Cloud Flashes"

Visar resultat 1 - 5 av 11 avhandlingar innehållade orden Cloud Flashes.

  1. 1. Broadband and HF Radiation from Cloud Flashes and Narrow Bipolar Pulses

    Författare :Noor Azlinda Ahmad; Vernon Cooray; Farhad Rachidi; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; Lightning; Cloud Flashes; Narrow Bipolar Pulses; HF radiation; Other physics; Övrig fysik; Engineering Science with specialization in Atmospheric Discharges; Teknisk fysik med inriktning mot atmosfäriska urladdningar;

    Sammanfattning : Remote measurement of electric field generated by lightning has played a major role in understanding the lightning phenomenon. Even though other measurements such as photographic and channel base current have contributed to this research field, due to practical reasons remote measurements of electric field is considered as the most useful tool in lightning research. LÄS MER

  2. 2. Characterizations of ground flashes from tropic to northern region

    Författare :Zikri Abadi Baharudin; Vernon Cooray; Mahbubur Rahman; Farhad Rachidi; Uppsala universitet; []
    Nyckelord :ENGINEERING AND TECHNOLOGY; TEKNIK OCH TEKNOLOGIER; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Positive negative cloud-to-ground lightning flashes; Initiation position; slow field changes; close ground flashes; preliminary breakdown process; Engineering Science with specialization in Atmospheric Discharges; Teknisk fysik med inriktning mot atmosfäriska urladdningar;

    Sammanfattning : This thesis portrays new information concerning the cloud-to-ground (CG) lightning flashes or ground flashes produced by thunderclouds. It emphasizes the importance of characterizing lightning studies as the relationship between lightning mechanisms, and of incorporating the influence of geographical location, latitude and storm type. LÄS MER

  3. 3. Broadband and HF radiation from cloud flashes and narrow bipolar pulses

    Författare :Noor Azlinda Ahmad; Uppsala universitet; []
    Nyckelord :TECHNOLOGY; TEKNIKVETENSKAP;

    Sammanfattning : Remote measurement of electric field generated by lightning has played a major role in understanding the lightning phenomenon. Even though other measurements such as optical, photographic, channel base current and thunder signatures have contributed in this regards, due to practical reasons remote measurements of electric field is considered as the most useful tool in lightning research. LÄS MER

  4. 4. Features and Origin of Electromagnetic Fields Generated by Lightning Flashes

    Författare :Mohd Muzafar Ismail; Vernon Cooray; Farhad Rachidi; Uppsala universitet; []
    Nyckelord :negative cloud-to-ground lightning flashes; HF and VHF radiation; chaotic pulse trains; lightning initiation; zero-crossing time; electromagnetic fields; Engineering Science with specialization in Atmospheric Discharges; Teknisk fysik med inriktning mot atmosfäriska urladdningar;

    Sammanfattning : Negative cloud-to-ground (CG) lightning flashes transport negative charge from cloud to ground. Negative ground flashes typically involve various processes identified as preliminary breakdown, stepped leader, return stroke, dart leader, dart-stepped leader, subsequent return stroke, and cloud activity between strokes, such as regular pulse trains and chaotic pulse trains. LÄS MER

  5. 5. Features of the Electric Fields Generated by Lightning with Special Attention to Positive Ground Flashes

    Författare :Dalina Johari; Vernon Cooray; Mahbubur Rahman; Fridolin Heidler; Uppsala universitet; []
    Nyckelord :NATURAL SCIENCES; NATURVETENSKAP; NATURVETENSKAP; NATURAL SCIENCES; positive ground flashes; preliminary breakdown pulses; multiple-trains PBPs; positive leader; bidirectional leader; negative leader branch; subsequent return strokes; distant lightning; Engineering Science with specialization in Atmospheric Discharges; Teknisk fysik med inriktning mot atmosfäriska urladdningar;

    Sammanfattning : This thesis focuses on the main processes in positive ground flashes and the distant lightning environment for both positive and negative ground flashes. It presents the characteristics of the preliminary breakdown pulses (PBPs), the characteristics of the electric field pulses observed during leader propagation, and the characteristics of the electric fields produced by the first and the subsequent return strokes. LÄS MER