アラビア半島を形作る自然環境に関して、この節では山地、含塩湿地（サブハ）、礫原、干潟、地層水等について旅をして行きます。なお、涸れ谷、砂丘と気候については、「第1部 大地の脈動を旅する」と「9 気候」で、すでに述べました。動植物にそれぞれついては、「11 植生」と「12 動物」で、別途述べます。
This section describes mountains, sabkhas, gravel plains, tidal flats and ground water, except wadis, sand dunes, climate, flora and fauna. They form the natural environment of this Peninsula. For wadi and sand dunes, see Part1 “Pulsation of Mother Earth”. For climate, refer to Chapter “9. Climate”. For flora and fauna, they are respectively described in Chapters “11. Vegetation” and “12. Animals”.
目次
アラビア半島内陸部
内陸部ナジュドの夏は長く暑く殆ど乾燥しています。冬には最低気温が零下7℃まで下がる事もあります。吹き抜ける風は水分が殆ど奪われているので降雨は極端に少なくなります。夏の卓越風は南から吹くシムーン（ハムシーン）です。シムーンは、完全に乾燥して沙塵を含んでいます。冬には冷たい乾いたシャマールが北方の中央アジアから吹いて来ます。シャマールは冬の終わりには地中海東部から進んでくる低気圧によって遮られます。この低気圧がナジュドに乏しい雨を生み出してくれます。
ナジュド北のジャウフ地方では冬は寒く、夏は暑く乾燥しています。冬には降雪があり、際だった特徴は風になります。卓越風向は冬が東で、春が西です。冬の南東からの風は雨を降らせ、北又は西からの風が寒さをもたらします。
ナジュドのさらに南のルブア・ハーリー沙漠では10年間全く雨が降らない事もあります。半面、数年あるいは数十年に一度は沙漠が洪水で溢れる記録も残されています。夏は日陰でも50℃以上にもなります。地表は80℃近くもあって生物がその上を移動できなくなります。夜に成ると空気は急速に冷やされます。寒い季節では凍り付いてしまうことも度々です。
The Inland Arabian Peninsula
The typical climate of the peninsula is that of the Najd region. That said, the climate is also different between the northern Najd and the southern Najd.
The Najd region is located in the inland of the peninsula. Its summer is long, hot and almost arid. Its temperature rises up to above 40°C. The prevailing wind in summer is called simoom (khamsin), which blows from the south. Simoom is completely dry and contains dust.
On the other hand, in winter, it is cold and it is felt more colder than the actual temperature because of dryness. In sometimes there are snowfall and freezing. The minimum temperature may drop to – 7°C below zero. As the wind, that blows through it, is almost completely deprived of water, the rainfall is extremely low. In winter, cold dry shamals come from central Asia in the north. The winter shamal is blocked by a low pressure from the eastern Mediterranean at the end of winter. This low pressure produces a little rain in the Najd region.
In the Jawf region, north of the Najd region, it is cold in winter, and hot and arid in summer. There is snowfall in winter. Above all, its strong wind is its characteristic feature. The prevailing wind direction is east in winter and west in spring. Winds from the southeast of winter make it rain, and winds from the north or west bring cold.
In Rub’ al Khali further south of the Najd region, there may not have been any rain at all for 10 years. Conversely, there is also a record of flooding the desert once every few years or decades. In summer, even in the shade, its temperature can rise to more than 50°C. The surface of the desert is close to 80°C, and any creature can’t move on it. At night, the air cools rapidly down. And, it often freezes in the cold season.
アラビア半島東部
クウェイトは、アラビア半島東海岸のアラビア湾側北部に位置します。地球上でも最も暑い場所の1つです。最高気温は、54.4℃を記録しています。 南東からの湿った風が6~10月まで吹きます。「この南東風は、半島南岸に吹く南西モンスーンに由来しています。南西モンスーンは、半島中央部では、北東からの貿易風の影響によって、南風に変えられます。アラビア湾では、ハジャル山脈とザグロス山脈が影響して、この南風が南東風に変えられている」と、筆者は考えています。暑く乾いた南風が春と初夏に卓越します。6~7月に共通して吹く北西風（シャマール）は、劇的な沙嵐の原因と成ります。
ハサーおよびカティーフ地方は、アラビア湾側の中部のにあります。夏は極端に暑く乾燥します。強烈な日差しが5~9月までの長い夏を典型的に作り出します。そして、時として大地の乾燥で沙嵐が発生します。冬の気温の低い曇った夜は、多くの露が発生します。夏には乾いた北西からのシャマールが卓越して吹きます。9月からは地中海からの低気圧の東への移動が次第に増して来ます。この低気圧は、遠く南はラアス・タヌーラまで影響を与えます。降雨の多いのは12月と1月です。局地的な嵐や強い風も珍しくありません。日中でも寒い日もあります。
バハレインは、ハサーの沖合にあります。シャマールよって沙嵐が運ばれて来て6月と7月の視界を悪化させます。バハレインを取り巻く海は非常に浅く、夏には直ぐに温められます。その暖められた海水が、特に夜間に高い湿度を作り出します。そのため、非常に蒸し暑くなります。
アラブ首長国連邦(U.A.E)は、アラビア湾側南部にあり、亜熱帯気候とも言えます。夏は乾燥して暑いですが、冬は温暖で穏やかです。ハジャル山脈では標高が高いので気温は相当に低くなります。夏の遅い月々の間は、湿気の多い南東の風シャルキーが吹きます。この南東の風は、海岸地方を特に不快にします。夏の月の間には猛烈な雨が降ることがあります。猛烈な雨は、通常は乾いた涸れ谷の河床に洪水をもたらすこともあります。この地方にも時折、視界を著しく遮る程の猛烈な沙嵐が来襲します。
The Eastern Arabian Peninsula
Kuwait is located in the northern Arabian Gulf on the east coast of the Arabian Peninsula. It is one of the hottest places on earth. The maximum temperature is 54.4 ℃. A moist wind from southeast blows from June to October.
The writer suppose personally as follows;
“This southeasterly wind comes from the southwestern monsoon that blows on the southern coast of the Arabian Peninsula. The southwestern monsoon is transformed into a southerly wind in the central Arabian Peninsula by the influence of trade winds from northeast. In the Arabian Gulf, the Hajar and Zagros Mountains affect this southerly wind and change into a southeastern wind.”
The hot and dry southerly winds predominate in spring and early summer. The northwesterly wind (Shamal), which commonly blows from June to July, causes a dramatic dust storm.
Hasa (Ahsa) and Qatif regions are located in the eastern coast of the central Arabian Peninsula. Summers are extremely hot and dry. Intense sunshine typically creates a long summer from May to September. And sometimes dust storms occur due to the earth dryness. Many dews occur on cold, cloudy nights in winter. Shamal from the dry northwest blows predominantly in summer. From September, the cyclones originated in the Mediterranean will gradually increase their movement to eastward. Those cyclones affect far south to Ras Tanura. They rain a lot in December and January. Local storms and strong winds are not uncommon. There are also cold days even in during the day in winter.
Bahrain is off the Hasa coast. Storms are brought in there by Shamals and impair visibility in June and July. The sea surrounding Bahrain is very shallow and can be warmed up quickly in summer. The warmed seawater creates high humidity, especially at night. Therefore, it becomes very hot and humid.
The United Arab Emirates (U.A.E) is located in the southern Arabian Gulf and has a subtropical climate. Summers are dry and hot, but winters are warm and mild. Due to the high altitude in the Hajar Mountains, the temperature is considerably lower. During the late summer months, the humid southeasterly wind called as Sharky blows. This southeastern wind makes the coastal regions particularly uncomfortable. Heavy rains can occur during the summer months. Heavy rains can also cause floods in the riverbeds of normally dry wadi valleys. Occasionally, the region is also hit by a fierce dust storm that significantly obstructs visibility.
アラビア半島西部
ターイフは、西海岸の紅海側のサラワート山脈山稜部にあります。標高の高さが穏やかな温度に寄与しています。紅海から内陸へと移動する湿った空気の大部分は山腹で上昇気流となります。上昇気流の水分は凝縮して雲を作ります。その雲が山稜の縁を通り過ぎる時に水分を落として雨を降らせます。ジェッダは、ティハーマ低地にあります。国際的にも悪名高い暑苦しさが特徴です。ジェッダでは降雨は、不規則で定まりません。
半島南西部はケッペンの気候区分(BWh)に含まれていません。アシールは、半島南西部の北部分を占めています。他の地方と異なり、山岳地帯で降雨が比較的豊富です。このためにティハーマ低地と山岳地帯での温度差が大きくなっています。ジーザーンは、ティハーマ低地の紅海岸にあります。世界中でも最も暑い場所の一つで、湿度も高くなります。高山地帯では北に行くほど涼しくなり、頼りの降雨は年に2回降ります。1回は紅海を通り抜けて来る北西風が運ぶ冬の雨であり、もう1回は夏のモンスーン（季節風）に運ばれてくる雨です。アシールの全域でこの両方の降雨の恵みを受けますが、北西風に運ばれてくる雨は南に下るに連れて極端に減ってくるのに反し、夏の雨は増してきます。
中央高地や西部高地は、南西アラビア半島南部のイエメン領に属しています。降雨量は標高によって大きく変わってきます。高地は気候が温暖です。年間降雨量は首都サヌアでは約300mmです。南イエメンの最も標高が高い地域では520~760mmもあります。特にイッブやタイズでは1,000~1,500mmに達します。海岸地方の気候は熱帯性で、温度が非常に高くなります。ティハーマ（西部海岸低地）の気温は時に54℃を越えます。湿度は50~70%の範囲です。不規則に非常な土砂降りとして降る雨もあります。それでも、降雨量は年間平均130mmに過ぎません。
The Western Arabian Peninsula
Taif is located on the ridge of the Sarawat Mountains on the Red Sea side (the western coast.) The height of the altitude contributes to its calm temperature. Most of the moist air moving inland from the Red Sea is up drafting on the mountainside. The moisture in the updraft air condenses and creates clouds. When the clouds pass through the mountain ridge, it drops moisture and makes it rain.
Jeddah is located in the Tihama lowlands. It is characterized by hot and humid that is notorious internationally. In Jeddah, rainfall is irregular and uncertain.
The southwestern part of the peninsula is not included in the Köppen climate classification (BWh). The Asir region occupies the northern part of the southwestern part of the peninsula. Unlike other regions, rainfall is relatively abundant in the mountainous areas. For this reason, the temperature difference between the Tihama Lowlands and the mountainous areas is large. As Jizan is located on the Red Sea Coast of the Tihama Lowlands, it is one of the hottest places in the world and has high humidity. In the high mountainous areas, such as Abha, the more you go north, the cooler it gets. And the reliable rainfall occurs twice a year. One is the winter rain brought by the northwestern wind, passing through the Red Sea, and the other is the summer rain, brought by the summer monsoon. The both of the rains are received throughout the Asir region. While the winter rain, brought by the northwestern wind, decreases extremely as descending south, but the summer rains are increasing.
The Central Highlands and Western Highlands belong to the Yemen territory in the southwestern Arabian Peninsula. The rainfall varies greatly depending on the altitude. The climate is relatively mild in the highlands. The annual rainfall is about 300mm in the capital Sana’a. The high-altitude areas of South Yemen can have the annual rainfall of as high as 520 to 760 mm. Especially in Ibb and Taiz, the annual rainfall can reach 1,000 to 1,500 mm. The climate of the coastal region is tropical and the temperature is very high. Temperatures in the Tihama Lowlands (the western coastal lowlands of the Peninsula) sometimes exceed 54°C. Their humidity ranges are from 50 to 70%. There is also rain that falls irregularly as a very downpour. Still, the rainfall averages are only 130mm per year.
アラビア半島南部
半島南海岸のアラビア海側に面しているのはイエメンとオマーンです。イエメンでは西部が湿潤で、東部が乾燥しています。ルブア・ハーリー沙漠近傍の北部や東部では5年以上も雨が降らないことも少なくありません。涸れ谷ハドラマウトは乾燥して暑くなります。オマーンも世界で最も暑い気候の国の1つです。降雨が稀で、その殆どが1月に降ります。ただ、アカダル山脈（ハジャル山脈の一部）では降雨量が400mmを超えています。山岳地帯の低温は数年ごとに積雪も記録しています。海岸地方、特にマシーラ島付近では時に一年を通して全く降雨が無いこともあります。気温は、非常に暑いことが普通です。5~9月までの暑い季節には50℃付近までに達します。但し、ドファール山脈（カーラ山脈）地域は、熱帯に似た気候です。インド洋のモンスーンの影響で、6~9月の終わりまで夏の空気を涼しい湿り気と厚い霧で満たします。季節的な降雨もあります。サラーラの夏の気温は20~30℃の間であり、北部オマーンに比べると相当に涼しくなります。
The Southern Arabian Peninsula
Yemen and Oman face the Gulf of Aden as well as the Arabian Sea. Those are off the southern coast of the Peninsula.
In Yemen, it is moist in the western region and it is dry in the eastern region. It often doesn’t rain for more than five years in the north or east regions near Rub’ al Khali. It is dry and hot in the Wadi Hadramaut region located in the southern central of the country.
Oman has also one of the hottest climate countries in the world. Rainfall is quite rare. Even if it has rains, the most of which falls in January. Nevertheless, the Jabal Akhdar (a part of the Hajar Mountains) has rainfall exceeding 400 mm. The low temperature in the mountainous area causes the record of the snowfall every few years.
There may be no rainfall at all throughout the year in the coastal areas, especially around the Masirah Island. The temperature is generally very hot. In the hot season from May to September, it reaches as high as around 50°C. However, the Qara Mountains region has a tropical climate. Due to the influence of the Indian Oceanic monsoon, the summer air is filled with cool moisture and causes thick fog in this region from June to the end of September. There is also seasonal rainfall. The summer temperatures in Salalah are between 20 ~ 30 ℃, which is considerably cooler than that of the northern Oman.
Desert peninsula 