Greenhouses are a crucial part of modern agriculture, especially in regions where the climate isn’t ideal for growing crops year-round. By regulating temperature, humidity, and light, greenhouses create an environment that’s much more suitable for plant growth. But exactly how much warmer is it inside a greenhouse compared to outside? Let’s dig into the fascinating science behind this temperature difference!
Why Does a Greenhouse Trap Heat?
The reason a greenhouse stays warmer than the outside lies in its clever design and construction. Most greenhouses are made from transparent or semi-transparent materials like glass, polycarbonate, or plastic films. These materials allow sunlight to pass through, where the shortwave radiation is absorbed by the plants and soil, converting it into heat. However, this heat gets trapped because it can’t escape as easily as the shortwave radiation that came in. This phenomenon is what we call the greenhouse effect.
For instance, the glass greenhouse at Alnwick Garden in the UK stays around 20°C inside, even when the outside temperature is just 10°C. Impressive, right?
Factors That Affect the Temperature Difference in Greenhouses
Of course, the temperature difference between the inside and outside of a greenhouse isn’t always the same. Several factors come into play:
1. Material Choice
The insulation ability of a greenhouse varies depending on the material. Glass greenhouses are excellent at trapping heat, but they come at a higher cost, while plastic film greenhouses are more affordable but less efficient at insulation. In California, for example, plastic film greenhouses used for vegetable cultivation can be 20°C warmer than the outside during the day, but they lose heat faster at night. Choosing the right material depends on your specific needs.
2. Weather and Seasonal Variations
The weather and seasons play a big role in the temperature difference. During harsh winters, a well-insulated greenhouse becomes essential. In Sweden, where winter temperatures can drop to -10°C, a double-glazed greenhouse can still maintain an interior temperature between 8°C and 12°C, ensuring plants continue to grow. On the other hand, in summer, ventilation and shading systems are vital to prevent overheating.
3. Greenhouse Type
Different types of greenhouses also create different temperature conditions. For example, in tropical Malaysia, sawtooth greenhouses are designed with natural ventilation in mind, keeping the internal temperature only 2°C to 3°C warmer than the outside during hot days. In more enclosed greenhouse designs, this difference can be much larger.
4. Ventilation and Humidity Control
Proper air circulation can significantly impact the temperature inside a greenhouse. If there’s little to no ventilation, temperatures can rise dramatically. In Mexico, some tomato-growing greenhouses use evaporative cooling systems like wet walls and fans to keep the internal temperature around 22°C, even when it’s 30°C outside. This helps create a stable growing environment, preventing plants from overheating.
How Much Warmer Is It Inside a Greenhouse?
On average, the temperature inside a greenhouse is typically 5°C to 15°C higher than outside, but this can vary based on the conditions. In Spain’s Almería region, where many greenhouses use plastic film, the interior temperature can be 5°C to 8°C warmer than the outside during the summer. When outside temperatures are 30°C, it’s usually about 35°C inside. In the winter, when it’s around 10°C outside, the temperature inside can remain a comfortable 15°C to 18°C.
In northern China, solar greenhouses are commonly used for vegetable farming during the winter. Even when it’s -5°C outside, the interior temperature can be maintained between 10°C and 15°C, allowing vegetables to thrive even in the cold.
How to Control the Greenhouse Temperature Effectively?
Since so many factors affect the temperature inside a greenhouse, how can we best control it?
1. Using Shade Nets
In hot summers, shade nets can significantly reduce the intensity of direct sunlight, lowering the internal temperature by 4°C to 6°C. In Arizona, for instance, flower-growing greenhouses ely on shade nets to protect delicate blooms from the intense heat.
2. Ventilation Systems
Proper ventilation is crucial for maintaining a comfortable temperature. In France, some grape greenhouses use top vents and side windows to promote airflow, keeping the internal temperature just 2°C warmer than outside. This prevents the grapes from overheating during ripening.
3. Heating Systems
During colder months, heating systems become essential for maintaining the right conditions. In Russia, for example, some greenhouses use underfloor heating to keep temperatures between 15°C and 20°C, even when it’s -20°C outside, ensuring that crops can grow without interruption through the winter.
How Temperature Affects Plant Growth
Maintaining the right temperature inside a greenhouse is critical to optimizing plant growth. In the Netherlands, cucumber greenhouses keep the temperature between 20°C and 25°C, which is the ideal range for cucumbers. If it gets too hot, plant growth can be stunted. Meanwhile, Japanese strawberry greenhouses use precise temperature control to keep daytime temperatures at 18°C to 22°C and nighttime temperatures at 12°C to 15°C. This careful regulation results in strawberries that are not only large but also deliciously sweet.
The Magic of Greenhouse Temperature Differences
The ability to control temperature is what makes greenhouses such powerful tools for modern agriculture. Whether it’s extending the growing season, improving crop quality, or simply surviving through harsh weather, the magic of temperature difference inside a greenhouse enables plants to flourish where they otherwise couldn’t. Next time you see a thriving plant inside a greenhouse, remember—it’s all thanks to the warmth and protection of that temperature-controlled environment.
Email: info@cfgreenhouse.com
Phone number: +86 13550100793
Post time: Oct-23-2024
