How Climate Shapes the Flavour of Tea

When it comes to tea, it is a very simple yet complex component. To the naked eye, it is something that you simply grow, harvest, process, and drink. But did you know that multiple chemical compounds affect the flavor of the tea? Variations in temperature, sunlight, and rainfall alter how tea plants synthesize these key compounds, creating the distinct flavor profiles. Same plant, same elements, but a different chemistry. The bush might be the same, but the quality of tea it produces each season can vary widely; hence, like wine, tea has a different vintage every year. Some essential chemical compounds are responsible for shaping the flavor profile of a tea. They are:

CATEGORY	COMPOUNDS	CONTRIBUTION TO THE FLAVOR
Amino Acids	L-theanine	Sweetness, smooth umami, relaxation
Polyphenols	Catechins, Tannins	Astringency, bitterness,  antioxidant capacity
Methylxanthines	Caffeine	Bitterness, mental stimulation, "briskness"
Volatiles (VOCs)	Linalool, Geraniol	Aroma (floral, fruity, earthy, sweet notes)
Carbohydrates	Simple Sugars	Natural sweetness, roasted/nutty notes during drying
Pigments	Chlorophyll, Carotenoids	Leaf color, grassy tones, aromatic precursors
Oxidized Polyphenols	Theaflavins, Thearubigins	Red/brown color, body, crispness in black teas

TEMPERATURE

RAINFALL

Rainfall, just like temperature, is another important factor that has a major influence on the taste of tea. The bushes generally do best with a rainfall lying between 1500 mm and 2500 mm. Adequate rain promotes quick budding and, as a result, leads to several harvests, or 'flushes', during the growing season. When there is not enough rain, the bush is forced into a protective resting period, which in turn slows down the emergence of the shoots and greatly reduces the yield. In short, more rain causes the tea to grow faster while less rainfall hinders the growth of the bush.

When tea grows slowly, and there is no heavy rainfall to dilute the sap, volatile aromatic essential oils build up to high concentrations, giving low-rainfall teas their characteristic floral notes associated with spring blossoms. For example, Darjeeling First Flush.

Heavy rainfall during the monsoon season speeds growth, causing the shoots to mature too quickly and thus fail to develop the complex flavour compounds. The continuous rainfall dilutes both the plant's essential oils and its soluble sugars, leading to a brew that has a greatly diminished aroma and little natural sweetness. The resulting leaves are more intense, bitter, and astringent.  Hence, monsoon flush teas are full-bodied but much less nuanced than those from spring or summer harvests.

HUMIDITY

High relative humidity and atmospheric mist are of great importance in determining the growth and chemical composition of leaves. It reduces transpiration, thus keeping the shoots tender. Direct sunlight is diffused, slowing down photosynthesis, and moisture reaches the leaves without waterlogging the roots.

In high-altitude areas such as Darjeeling, frequent cloud cover filters the sunlight and helps to preserve L-theanine and the volatile aromatic oils. Giving the tea its characteristic floral, sweet, and "muscatel" flavour. 

On the other hand, in low-elevation areas such as Assam, where there is a lack of mist and humidity, the bushes are exposed to strong sunlight and heat, leading to high activity of the PAL enzyme, which quickly converts amino acids into bitter catechins and polyphenols, resulting in a bold, malty and astringent tea with a deep-copper coloured liquid that goes well with milk.

TERRIOR

The character of a tea is also influenced by terroir in that the composition of the soil, the elevation, the topography, and the local microclimates of the estates. 

All have a direct effect on the plant's metabolism and chemical synthesis. Soils that are acidic and rich in minerals and that drain well allow for effective nutrient absorption. The direction of the slope determines the amount of sunlight the plants receive and the rate of drainage, thus preventing waterlogging. 

Lastly, the local micro-environments - such as cloud cover and the vegetation in the surrounding forests- all contribute unique regional characteristics and complex aromatic profiles that cause each growing region's tea to be different.

DIFFERENT SEASONS - DISTINCT FLAVORS

The seasonal shift in weather directly drives the progression of tea harvest cycles, transforming how each distinct flush tastes and behaves in the cup:

In spring, the tea bushes emerge from their winter dormancy due to the cool temperatures, the low rainfall, and the soft morning mist, and grow slowly. The outcome is a light, luminous, and highly valued brew noted for its floral sweetness, crisp freshness, and subtle "muscatel" notes.

In early summer, when the temperature increases and moderate rains start, cellular growth speeds up. It has an excellent balance achieved between the rate of growth and the accumulation of compounds, resulting in a cup that is fuller-bodied and more well-rounded, with stronger fruit flavours, an amber-coloured brew, and a more noticeable, typical muscatel flavour.

During the monsoon season, the combination of heavy and continuous rain with high temperatures leads to very rapid and uncontrolled vegetative growth. Leaves that are harvested when the moisture content is high, since they come from quickly growing plants, make a dark, heavy brew with minimal subtle aromas and are therefore most suitable for use in strong blends.

Autumn Flush (Post-Monsoon): When the intense monsoon rains have stopped, and the air temperatures start to fall, the plant's growth slows down once more. The leaves picked during this dry and crisp period give a combination of a mature body and a gentle accumulation of aromatic compounds, resulting in a smooth liquor of copper colour with rich, earthy and warm woody flavours.