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1 夜间云的特征及观测要领 首先,必须了解当天傍晚云的发展与变化规律。入夜前,仔细观测云的分布情况,根据本地云状的一般演变规律,分析以后可能出现的云状,做到心中有数。如果傍晚云的性质稳定,并且变化不大,则夜间可能继续保持着。例如AS、CS、NS、SC等,这些云持续性比较强,出现后不易在较短时间里变化为其他云属,在未发生转折性天气变化前,可以运用它们持续性强这一特点,来进行判断。如果白天是对流云,就可根据傍晚观测云是发展还是衰退,来判断夜间可能演变为什么云状。例如,傍晚时观测某方向有Cb云趋于减弱,入夜后多呈灰色条状,… 相似文献
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1准备观测 首先了解云的发展情况或演变规律,注意白天云的演变过程及黄昏前的变化趋势,大致推断它可能转变的形式,然后再与实际情况结合进行判断.如白天全天都是对流云,黄昏仍不衰退,夜间就可能有这类云的存在和发展,甚至有雷雨;如果黄昏已衰退,那么夜间可能有残存的CL4、CM6、CH3的云.又如黄昏CH4的发展很快,夜间可能有CH5、CH6、CH7,甚至CM1、CM2等,这种云也可能发展到任一阶段就开始消散,而转为CH8、CH2、CH1等.另外也有一些相互转变的云,如CH7←→CH2、CL5←→CM2等. 相似文献
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云的种类繁多,千变万化,纷繁复杂。在观测中,要正确辨别,必须从云的内在结构、外部特征、演变规律以及伴见的天气现象等留心观察,仔细分析,不断总结经验。要特别注意相似云的辨别,不要混淆。在夜间观测时,要常注意云的连续演变及伴见的天气现象,尽可能利用一切条件,综合识别。 相似文献
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夜间观测云时,最好在没有灯光的情况下进行。进入观测点后,应停留片刻待瞳孔放大,天空状况渐渐看清以后再进行观测。掌握云的连续变化对确定夜间云状是有帮助的。入夜前,仔细观测云的分布情况,根据本地云状的一般演变规律,分析以后可能出现的云状,做到心中有数。例如,入夜前观测某方向有积云趋于减弱,入夜后演变为条状,就可考虑是否是积云性层积云。又如入夜前为卷层云,入夜后呈均匀幕状不见星月,这就可考虑记高层云。运用云的持续性识别云。有些云出现后往往持续时间较长,如A_s、C_s、N_s、S_c等,在未发生转折性天气变化前,我们可以运用它们的这一特点,来进行判辨。 相似文献
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1 准备观测首先了解云的发展情况或演变规律 ,注意白天云的演变过程及黄昏前的变化趋势 ,大致推断它可能转变的形式 ,然后再与实际情况结合进行判断。如白天全天都是对流云 ,黄昏仍不衰退 ,夜间就可能有这类云的存在和发展 ,甚至有雷雨 ;如果黄昏已衰退 ,那么夜间可能有残存的ＣＬ4、ＣＭ6、ＣＨ3的云。又如黄昏ＣＨ4的发展很快 ,夜间可能有ＣＨ5、ＣＨ6、ＣＨ7,甚至ＣＭ1、ＣＭ2等 ,这种云也可能发展到任一阶段就开始消散 ,而转为ＣＨ8、ＣＨ2、ＣＨ1等。另外也有一些相互转变的云 ,如ＣＨ7←→ＣＨ2、ＣＬ5←→ＣＭ2等。其次 ,利用天气形… 相似文献
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云是较难目测的项目之一。尤其是在无星光和月光的黑夜 ,常让观测员感到焦急。但只要用心观察 ,不断总结经验 ,就会发现云的演变其实是有规律的。运用这些规律 ,就能逐步提高对云的目测水平。在无星光和月光的夜晚 ,可结合云的一些特点来判断云状、云层( 1 )云具有联系性 ,即根据云的连续变化和演变规律来判别云状。一般在傍晚时 ,应对云进行仔细观察 ,待夜间正点观测时 ,可根据傍晚时云的发展趋势判断出云状。例 :傍晚测站某方向有Ｃｕ云趋于减弱 ,观测时云呈条状 ,就可有把握地判定是Ｓｃ云。又 :傍晚为Ｃｓ云 ,观测时呈均匀云幕 ,不见星… 相似文献
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我局从1999～2003年,测报工作连续4年未出现错情,在此期间共有1个250个班,9个百班无错通过上级业务部门验收.在仪器保管、使用、维护上符合要求,对外报送的各种表、簿都能做好出门合格. 相似文献
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Comparing the theoretical versions of the Beaufort scale, the T-Scale and the Fujita scale 总被引：1，自引：0，他引：1
G. Terence Meaden S. Kochev L. Kolendowicz A. Kosa-Kiss Izolda Marcinoniene Michalis Sioutas Heino Tooming John Tyrrell 《Atmospheric Research》2007,83(2-4):446-449
2005 is the bicentenary of the Beaufort Scale and its wind-speed codes: the marine version in 1805 and the land version later. In the 1920s when anemometers had come into general use, the Beaufort Scale was quantified by a formula based on experiment. In the early 1970s two tornado wind-speed scales were proposed: (1) an International T-Scale based on the Beaufort Scale; and (2) Fujita's damage scale developed for North America. The International Beaufort Scale and the T-Scale share a common root in having an integral theoretical relationship with an established scientific basis, whereas Fujita's Scale introduces criteria that make its intensities non-integral with Beaufort. Forces on the T-Scale, where T stands for Tornado force, span the range 0 to 10 which is highly useful world wide. The shorter range of Fujita's Scale (0 to 5) is acceptable for American use but less convenient elsewhere. To illustrate the simplicity of the decimal T-Scale, mean hurricane wind speed of Beaufort 12 is T2 on the T-Scale but F1.121 on the F-Scale; while a tornado wind speed of T9 (= B26) becomes F4.761. However, the three wind scales can be uni-fied by either making F-Scale numbers exactly half the magnitude of T-Scale numbers [i.e. F′half = T / 2 = (B / 4) − 4] or by doubling the numbers of this revised version to give integral equivalence with the T-Scale. The result is a decimal formula F′double = T = (B / 2) − 4 named the TF-Scale where TF stands for Tornado Force. This harmonious 10-digit scale has all the criteria needed for world-wide practical effectiveness. 相似文献
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准两年振荡对大气中微量气体分布的影响 总被引：11，自引：5，他引：6
NCAR的包含化学、辐射、动力相互作用的两维模式（SOCRATES）移植回国后进行了初步的模拟试验,用以研究某些对环境问题重要的微量气体的化学、辐射、动力传输过程。在不考虑极地平流层云和气溶胶表面非均相化学等情况下,模式积分多年,计算结果稳定,模拟的风场、温度场显示出正常的季节变化,模拟的微量气体分布与卫星实测资料对照,结果也比较一致。为了探讨热带平流层风场的准两年周期振荡（QBO）对平流层微量气体分布的影响,我们做了QBO强迫的数值试验,即在模式中加入QBO强迫,并与不考虑QBO强迫的模拟结果对比。结果表明,QBO与其相关的次级环流所引起动力输送的变化,使平流层微量气体分布发生变化。 相似文献
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The impact of high resolution modern vegetation cover on the West African climate is examined using the International Centre for Theoretical Physics Regional Climate Model implementing the NCAR Community Land Model. Two high resolution 25 km long-term simulations driven by the output from a coarser 50-km resolution simulation are performed for the period 1998–2010. One high resolution simulation uses an earlier and coarser-resolution version of plant functional type distribution and leaf area index, while the other uses a more recent, higher-quality, and finer-resolution version of the data. The results indicate that the new land cover distribution substantially alters the distribution of temperature with warming in Central Nigeria, northern Gulf of Guinea and part of the Sahel due to the replacement of C4 grass with corn; and cooling along the coastlines of the Gulf of Guinea and in Central Africa due to the replacement of C4 grass with tropical broadleaf evergreen trees. Changes in latent heat flux appear to be largely responsible for these temperature changes with a net decrease (increase) in regions of warming (cooling). The improved land cover distribution also results in a wetter monsoon season. The presence of corn tends to favor larger precipitation amounts via more intense events, while the presence of tropical broadleaf evergreen trees tends to favor the occurrence of both more intense and more frequent events. The wetter conditions appear to be sustained via (1) an enhanced soil moisture feedback; and (2) elevated moisture transport due to increased low-level convergence in regions south of 10N where the most substantial land cover differences are present. Overall the changes induced by the improved vegetation cover improve, to some extent, the performance of the high resolution regional climate model in simulating the main West African summer monsoon features. 相似文献
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由中国历史气候记录对季风导致唐朝灭亡说的质疑 总被引：1，自引：0，他引：1
张德二 《气候变化研究进展》2008,4(2):126-130
2007年1月4日杂志发表了Yancheva等10人的题为"Influence of the intertropical convergence zone on the East-Asian monsoon"(热带辐合带对东亚季风的影响)的论文[1],这是德国波兹坦地学研究中心气候动力与沉积学科的主管豪格(G.H.Haug)率领的科研小组的一项成果,认为是季风的变化引起的长期干旱导致了唐朝的灭亡. 相似文献
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流场配置及地形对西南低涡形成的动力作用 总被引：10，自引：8，他引：10
本文采用定常二层模式讨论较小地形及高、低层流场配置对西南低涡形成的动力作用。指出了西南低涡的形成是与盆地、河谷以及其上气流分层有关的一种定常态.在上、下为西风分层时期,低层的浅薄暖湿西风有利于西南低涡的形成.在上、下为东、西风分层时期,上层浅薄东风亦有利于西南低涡的形成.小型的凸起山脉对西南低涡的形成没有作用. 相似文献
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Summary ?Some features of the climate system that can be considered predictors of the onset and end of the convective season over
the Amazon were identified using one-month lag correlations and field composites. The fields analyzed were sea surface temperature
(SST), outgoing long-wave radiation (OLR), vertical velocity and upper tropospheric winds.
Warm (cold) anomalies in the SST in the tropical North Atlantic and the Caribbean Sea tend to be associated with delayed (early)
onsets. Likewise, there is a tendency towards a delayed (early) end of the convective season with cold (warm) anomalies in
these ocean regions. In addition, the SST in the cold tongue region of the equatorial Pacific is negatively, though weakly
correlated with the onset date. The signal of this SST is more evident in the case of the end date, which is earlier with
respect to its mean date in most of El Ni?o cases.
The convective activity intensity itself conditions the onset and the end of the convective season, as it is evidenced by
the behavior of the OLR and the vertical velocity fields. The more (less) intense the convective activity over South America
during the preceding month, the earlier the onset and the later the end of the convective season on the Amazon region.
The prediction of the onset and end dates of the convective season in the Amazon region was explored using a simple multiple
regression technique based on the variables that have shown precursor signals with respect to these dates. The correlation
coefficient between the predicted and the observed onset date is 0.81, and in the case of the end date, it is 0.76. The skill
to predict early, delayed and normal categories was high, since in more than two thirds of the cases the category was successfully
predicted, and there were no predictions of categories opposed to those observed.
Received July 23, 2001; revised February 22, 2002; accepted April 26, 2002 相似文献
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Chunguang CUI Wen ZHOU Hao YANG Xiaokang WANG Yi DENG Xiaofang WANG Guirong XU Jingyu WANG 《大气科学进展》2023,40(4):711-724
Here, we analyze the characteristics and the formation mechanisms of low-level jets(LLJs) in the middle reaches of the Yangtze River during the 2010 mei-yu season using Wuhan station radiosonde data and the fifth generation of the European Centre for Medium-Range Weather Forecasts(ERA5) reanalysis dataset. Our results show that the vertical structure of LLJs is characterized by a predominance of boundary layer jets(BLJs) concentrated at heights of 900–1200 m.The BLJs occur most frequently at 230... 相似文献