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METEOROLOGI

METEOROLOGIPelatihan OSK SMAN 2 TangerangTangerang, 14-15 Desember 2013Oleh : M. Reza Ardian TOIKI 2011

Disadur dari berbagai sumberKomposisi Atmosfer Dekat Permukaan Bumi

Permanen kadar tetapVariabel kadar berbeda-beda tergantung tempatUap AirGas variabel paling pentingMengontrol sebagian besar gejala-gejala cuacaKadar bisa hingga 4% di tempat yang benar-benar lembabTermasuk GRK

Transformasi Fasa Air

CO2

Sejarah Terbentuknya AtmosferKetika baru terbentuk, atmosfer bumi terdiri dari H2, He, serta senyawa ber-HGas lain? dari outgassing

N2 dan O2 dari mana?

Lapisan Atmosfer

TermosferMesosferStratosferTroposfer

Berdasarkan strukturtemperatur

TroposferRata-rata susut suhu sekitar 6,5C/kmKira-kira 80% total massa atmosferMengandung seluruh uap air dan aerosolKetinggian berbeda-beda (8-16 km) rt2 11 kmWell-stirred by convective air currentBoundary layerStratosfer

Lapisan inversi, shg not well-stirred & isotermalKarena??Lapisan O3serap UVTropopause s/d~50 km

MesosferMakin tinggi makin dingin50-80 kmSuhu terendah di atmosfer (-90C) pada mesopauseKebanyakan meteor yang sampai ke bumi biasanya terbakar di lapisan ini.99,9% massa atmosfer dibawah lapisan ini, shg sangat tipis

Termosfer80-500 kmKomposisi heterogenInversi akibat penyerapan radiasi oleh atom OTemperatur juga dipengruhi aktivitas matahari

EksosferMolekul ringan H2 bisa melepaskan diriO2, H2, He

Berdasarkan Komposisi

HomosphereNitrogen and oxygen are wellmixed (~78% and ~21%)

HeterosphereAtom berat diatas, atom ringan di bawahIonosferAtom-atom terionisasiXray, UV

Ionosfer dan Komunikasi

Unsur CuacaSuhuTekananKelembabanAwanPresipitasiVisibilitasAngin

TEMPERATURTemperatur

Kalor Spesifik

Kalor Laten

Transfer KalorKonduksiKonveksiRadiasi

Parsel udara naik ekspansi, mendinginParsel udara turun kompresi, memanas

Radiasi EM

Hukum Wien

max = 2897 m K / T(K)Albedo

Mengapa makin atas makin dingin?

GRKwater vapor, carbon dioxide, methane, nitrous oxide, and ozone.

Neraca Energi

Aurora

Insolation (Incoming Solar Radiation)

Lama Siang dan Malam

Empat Musim

Gerak Semu Matahari Berdasarkan Lintang

Net Radiation

HarianTahunanTEKANANTekanan

Profil Tekanan

Gaya Gradien Tekanan

Gaya Coriolis

Angin Geostrofik

Angin Gradien

Isobar

KelembapanUdara lembap = udara kering + uap air

Ukuran KelembapanKelembapan mutlak (g H2O / m3 udara lembap)Kelembapan spesifik (g H2O / kg udara lembap)Kelembapan relatif (RH)Mixing ratio (g H2O / kg udara kering)Tekanan uap & tekanan uap jenuhTitik Embun (Suhu dimana RH = 100%)Temperatur bola basahTemperatur bola keringTekanan Uap

RH

Titik EmbunDepresi titik embun = selisih T dengan TdT > TdDepresi titik embun berbanding terbalik dengan kelembapan

ContohSuatu parsel udara bersuhu 27C memiliki titik embun 21C. Berapa kelembaban relatifnya?Suatu parsel udara bersuhu 21C memiliki kelembaban relatif 84%. Berapa titik embunnya?

Pemanasan dan Pendinginan AdiabatikAdiabatik tidak ada kalor yang keluar masukKarena sifat udara yang menghantar kalor dengan burukAdiabatik Kering (10C/km)Adiabatik Jenuh (6,5C/km)Stabilitas AtmosferStabil dan Tidak Stabil

Pada UdaraStabil Jika diturunkan/ dinaikkan, kembali ke posisi semulaTidak stabil Jika diturunkan/ dinaikkan, jalan terus

Angin : Sirkulasi Global & LokalSkala Gerak Atmosfer

Sirkulasi 3 sel

-Hadley-Ferrel-KutubITCZ

Easterly windWesterly windAngin pasatDistribusi Presipitasi Berdasar Lintang

Turbulensi TermalParsel udara naik karena pemanasan permukaanBiasa terjadi tengah hari

Angin Fohn

Angin Fohn di berbagai daerahBahorok Dataran rendah Deli UtaraKumbang CirebonGending ProbolinggoGenggong PasuruanBrubu MakassarWambraw Biak

Gelombang Lee

Angin Darat Angin LautCp darat < Cp lautDarat lebih cepat menyerap & melepas kalorAkibatnya, pada siang hari daratan lebih cepat panasPada malam hari, daratan lebih cepat dingin

Angin Gunung Angin Lembah

KONDENSASI & AWANInti KondensasiDibutuhkan suatu partikel higroskopis untuk mengkondensasi uap airDebu, asap, SO2, garam, dsb0,001 mikron 10 mikron

KondensasiSebelum RH 100% jika ada inti kondensasiEfek larutan vs efek kelengkungan

Klasifikasi Awan

ENVI 1400 : Meteorology and Forecasting75High-Level CloudsCirrus (Ci): White, delicate, fibrous in appearance. Forms in patches or narrow bands. May for comma-shaped streaks or mares tails (cirrus uncinus)

Cirrus clouds are formed entirely of ice crystals. These grow and evaporate slowly, leading to soft edges to clouds.ENVI 1400 : Meteorology and Forecasting76

Cirrostratus (Cs): Thin, transparent sheet or veil; sun clearly visible & casting shadows at surface. A halo may be seen around the sun (or moon). Sheets of cirrostratus may cover entire sky, and be up to several 1000m deep.

ENVI 1400 : Meteorology and Forecasting77Cirrocumulus (Cc): Thin white patch or sheet of cloud; appears dappled or rippled. Dappling results from convective overturning within the cloud, ripples from gravity waves.

Aircraft contrails: condensation from aircraft exhaust. May dissipate quickly, or be very long-lived depending on conditions.ENVI 1400 : Meteorology and Forecasting78Medium-Level CloudsAltostratus (As): A greyish sheet of cloud, may be fibrous or uniform in appearance. Thin enough in parts to make out the sun, but no halo.

ENVI 1400 : Meteorology and Forecasting79Altocumulus (Ac): white or grey patches arranged in sheets. Shape and texture are variable.There are several distinct sub-classes of altocumulus

ENVI 1400 : Meteorology and Forecasting80Altocumulus lenticularis (Ac len): white or grey lenticular (lens shaped) clouds formed by the lifting of air over a topographic barrier.

ENVI 1400 : Meteorology and Forecasting81

Altocumulus castellanus (Ac cas): white or grey, broken cumulus-like clouds; upper part appearing castle-like. Sometimes arranged in lines.


Altocumulus undulatus (Ac und): white or grey patches or sheets of cloud with an undulating or rippled appearance.

ENVI 1400 : Meteorology and Forecasting83Low-Level Clouds

Cumulus (Cu): Brilliant white to grey, dense detached clouds. Forms clumped or heaped (cauliflower-like) shapes, usually with sharp outlines and flat base. Field of Cu often have bases all at same (lifting condensation) level.

ENVI 1400 : Meteorology and Forecasting84Cumulus humilis (Cu hum): small cumulus, of limited vertical extent, may have a flattened appearance. Also called fair-weather cumulus

ENVI 1400 : Meteorology and Forecasting85Cumulus mediocris : cumulus, of moderate vertical extent.


Cumulus congestus: crowded (congested) field of cumulus or greater vertical extent. May produce rain.ENVI 1400 : Meteorology and Forecasting87

Pileus : cap clouds that form above large cumulus as the upward motion of the convective cloud distorts the layer of air above (pileus is latin for skull-cap)ENVI 1400 : Meteorology and Forecasting88


Cumulonimbus (Cb) : huge towering cloud, dark base and white sides. Associated with heavy rain, thunderstorms, and hail. Frequently has an anvil shaped top.ENVI 1400 : Meteorology and Forecasting90

mammatus : smooth, rounded shapes sometimes formed on the underside of cumulonimbus; they result from downdrafts within the cloud.ENVI 1400 : Meteorology and Forecasting91Stratocumulus (Sc) : white or grey sheet of cloud, usually formed in mounds or rolls.




Stratocumulus with virga hair-like strands of falling rain, which evaporate below cloud before reaching the surface.ENVI 1400 : Meteorology and Forecasting95Stratus (St) : grey featureless layer of cloud with a uniform base. Often associated with drizzle or snow.

ENVI 1400 : Meteorology and Forecasting96Nimbostratus (Ns) : Dark grey, featureless, thick layer of cloud. Associated with prolonged precipitation. Commonly forms in frontal systems

Arcus

Fibratus

Inkus

LainnyaUndulatusFraktusFibratusKalvusKapilatusNebulosusTranslucidusUncinusdllSiklus Hidup Awan Kumulus

Presipitasi

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