Nepal has a diverse climate ranging from tropical (extremely hot) to arctic (extremely cold). All these can be found within a distance of approximately 180 km. The mountain ranges and their deep river valleys and gorges exhibit diverse climatic zones, which further increases the diversity of habitats due to the differences in precipitation (the quantity of water falling to earth), humidity, temperature and aspect. Precipitation in Nepal is brought by the summer monsoon and winter rains. The summer monsoon accounts for about 80% of the precipitation (June–September) and is accompanied by a northwesterly airflow from the Bay of Bengal. Most of the east and the lower hills and lowlands of central and western Nepal receive more than 80% of the annual total precipitation during the monsoon season.
Climatic Condition of Nepal
Climatic condition of any country or place is influenced by the different factors such as Latitude, Land feature, Mountain barrier, Distance from the sea, Vegetation etc. Condition of Climate in Nepal is also influenced of by above factors and generally climatic condition of Nepal can be divided into two conditions.
A. Summer season: when sun enter to north from the equator, summer season starts in Nepal. In this condition, day increases and night decreases slowly. Summer season is also divided into two parts which are:
- Hot dry season: In this season the temperature of Nepal begins to be hot due to the sun rays above the tropic cancer line. In this season the temperature in Terai and valley is very hot. But in the hilly region temperature is normal. Hot dry season in Nepal starts from late falgun and continue up to mid estha. It is mostly dry season. In this season, after 12 there is the possibility of thunder.
- Hot wet season: This type of climatic condition, in Nepal, Starts mid jestha (June) and continues up to Mid Bhadra (Precipitation in Nepal is brought by the summer monsoon in this season. The summer monsoon accounts for about 80% of the precipitation (June–September) and is accompanied by a northwesterly airflow from the Bay of Bengal (September).
B. Winter season: When sun enter to the south from equator, the winter season starts in Nepal. Due to the location of Nepal ( North Latitude) sun rays are straight and increases the cold in Nepal. This climatic condition continues up to Last Magh. Winter season is also divided into two category which are:
- Cool wet season: this season prevalent during the period of September to December. In this season air flows from the Mediterranean sea to Nepal and there is the possibility of Precipitation in Nepal. It is also known as post monsoon period.
- Cool dry condition: In this climatic condition, Sun remains above the Tocopic of Capicon (Makar Rekha). Being located in north Latitude, there is the very cold in Nepal and it is the dry season.
Types of Climate in Nepal
Nepal has a diverse climate ranging from tropical to arctic. The mountain ranges and their deep river valleys gorges, flat land, altitude, etc. Exhibit diverse climatic zones. There is an array of climatic zones along the vertical gradient of the mountain slope. Basically there are five types climatic zones are found in Nepal which are as follows:
1. Sub-tropical region: - Sub tropical climate is found from the sea level to the altitude of 1200 m. This type of climate is mostly found in Bhawar, Dun, Tarai, and other valley. In summer season the temperature of this region remains more than 35 degree Celsius. It is the hot area in Nepal. Sub-Tropical zone is characterized by hot and humid climate. The rainfall is less than in western part of Tarai due to the hot air flow of western part which also known as Loo.
2. Warm Temperate climate: - This type of climate is found from the altitude of 1200 m to 2100 m. In Nepal, it is mostly found in upper part of Chure, central part of Mahabharat and Midland. It has less temperature than the subtropical region. In the summer season the temperature remains between 24 degree to 30 degree Celsius. In winter 5 to 10 degree temperature is found in this region.
3. Cool Temperate climate: - This type of climate is found between the 2100m to 3300 m. It is mostly found in the upper land of Mahabharata and Lower part of Himalaya. Here we find the cold temperature with the growth of altitude. In summer season maximum temperature is about 20 degree Celsius and winter less than 5 degree Celsius.
4. Alpine Climate: - This type of climate is found between the altitudes between 3300 m to 5000 m from the sea level. This type of climate is found in upper Himalaya and inner Himalaya. The temperature of this region remains between 10 degree Celsius to 15 degree Celsius in summer season. In winter season less than 0 Degree Celsius. It is the cold region.
5. Tundra Climate: - This type of climate is found above the 5000 m from the sea level. There is always cold around the year in this region. It is always covered by the snow. It is not suitable place for human settlement. Here we find the tundra. It is also called cold desert due the lack of vegetation. It is also known as third pole of the world.
Types of Vegetation in Nepal
Vegetation refers to the specific type of plant life extended to over a specific area. Climate determines the vegetation of Nepal. The categorization and demarcation of vegetation is difficult because of the Complexity of physiographic and climatic zones in the region. Vegetation of Nepal can be classified into five types on the basis of climatic Zone which are as follows:
1. Sub-tropical forest: - This type of forest is found in the Tarai area of Nepal. The major types of forest in this eco-region are sal forest, tropical deciduous riverine forest, and tropical evergreen forest. Sal forest occurs throughout the flatlands of Tarai and is also present in the Siwaliks. Sal is the dominant species. However, the species composition of sal forests in the Siwalik region varies. Sal forests are replaced by tropical deciduous riverine forest along the banks of rivers and on river terraces. Similarly, this eco-region is characterized by wide range of savanna type grasslands, evergreen and deciduous forests, whose presence depends on the different climatic and moisture conditions prevailing here. Sal, Khayar, Sisau, Jamun, Tuni, Simal etc. are the major plants of this area. This eco-region includes five protected areas consisting of three wildlife reserves (Shukla Phanta, Parsa and Koshi Tappu) and two national parks (Bardiya and Chitwan).
2. Deciduous Monsoon Forest: - This type of forest is found in the warm temperate climatic region. We can find subtropical deciduous hill forest and subtropical semi-evergreen hill forest. This type of forest is found in upper part chure and the middle part of Mahabharata range. The trees shed their leaf in winter season. The major trees in this region are chilaune, Lakuri, Simal, Uttis, Kattush, Chap, Okhar etc.
3. Evergreen Coniferous forest: - This type of forest is found in the altitude of 2100 m to 3300 m from the sea level. Cheer, Pine, Devdaar, Nigalo, Gurans, Dhupi, Bhojpatra etc are the major kind of vegetation in this forest.
4. Alpine Grass land: - Alpine grassland is found in altitude between 3300 m to 5000m from the sea level. There is the grazing land. Herbs, Gurans, harsh Bushes etc. are found in this forest.
5. Tundra: - This type of vegetation is found at the altitude above 5000 m from the sea level. In this region, some herbs, Mosses, Lichen etc are found.