Preparing for camping in cold weather requires careful planning and the right gear to ensure safety and comfort amidst low temperatures. Understanding how to select appropriate clothing, equipment, and safety measures can make the difference between a memorable outdoor experience and a challenging ordeal.
This comprehensive guide covers essential clothing layers, specialized gear, safety considerations, warming techniques, food and hydration strategies, campsite setup, and environmentally friendly practices. By following these recommendations, outdoor enthusiasts can enjoy winter camping while staying warm, safe, and respectful of nature.
Essential Gear and Clothing for Cold Weather Camping

Preparing adequately for cold weather camping is crucial to ensure safety, comfort, and enjoyment during your outdoor adventure. The right combination of clothing and equipment can make the difference between an invigorating experience and a hazardous situation. Understanding the essential gear and clothing layers designed for low temperatures helps campers stay warm, dry, and protected against the elements.
In cold weather environments, the key to effective insulation and protection lies in selecting gear that offers thermal efficiency, moisture resistance, and durability. Proper layering is fundamental, as it allows versatility in regulating body temperature and adapting to changing weather conditions. Alongside clothing, specialized camping gear such as high-rated sleeping bags, insulated tents, and thermal mats provide essential support for a restful and safe night’s sleep in frigid conditions.
Clothing Layers for Cold Weather Camping
Implementing a layered clothing system is vital for maintaining body heat and managing moisture during cold weather camping. Each layer plays a distinct role, working together to provide insulation, wick away sweat, and shield against wind and moisture.
- Base Layer: This layer is closest to the skin and should be made of moisture-wicking materials such as merino wool or synthetic fabrics. It draws sweat away from the body, preventing chill caused by dampness. Lightweight and breathable, it forms the foundation for thermal regulation.
- Insulation Layer: The primary purpose of this layer is to trap body heat. Options include fleece, down, or synthetic insulated garments such as jackets and pants. They create a barrier that retains warmth even if they become slightly damp.
- Waterproof Outer Layer: This layer protects against wind, rain, and snow. Waterproof and breathable shells, such as Gore-Tex jackets and pants, prevent moisture penetration while allowing excess heat and humidity to escape, maintaining comfort and dryness.
Essential Camping Gear for Cold Conditions
In addition to layered clothing, specialized camping gear is necessary to combat extreme cold and ensure safety throughout the night. High-quality gear enhances warmth, stability, and protection in challenging environments.
- Sleeping Bags Rated for Low Temperatures: A cold-weather sleeping bag should have a temperature rating suitable for the anticipated conditions, typically designed to operate effectively at temperatures as low as -20°C (-4°F). Features include high-quality insulation such as goose down or synthetic fibers, draft collars, and insulated hoods to prevent heat loss.
- Insulated Tents: Tents built specifically for winter camping feature robust materials, strong frame structures to withstand snow loads, and sealed seams to prevent drafts. They often include vestibules for gear storage and interior pockets for organization.
- Thermal Mats: Insulating mats made from closed-cell foam or inflatable materials with thermal layers help prevent heat loss from the ground. Combining a thermal mat with a sleeping bag significantly improves warmth and comfort during cold nights.
Comparison of Cold-Weather Sleeping Bags
Choosing the right sleeping bag is essential for staying warm and comfortable. Below is a comparison of different types of cold-weather sleeping bags, highlighting their features and suitability for various conditions.
| Type of Sleeping Bag | Features | Temperature Rating | Ideal Use |
|---|---|---|---|
| Down Sleeping Bags | High warmth-to-weight ratio, excellent insulation, compressible, durable but less effective when wet | -20°C to -10°C | Backpacking in cold but dry conditions |
| Synthetic Sleeping Bags | Good insulation even when damp, easier to care for, generally heavier | -15°C to -5°C | Wet or humid environments, versatile use |
| Hybrid Sleeping Bags | Combine down and synthetic insulation to optimize warmth, weight, and moisture resistance | -20°C to -10°C | Extended cold weather camping with variable conditions |
“Selecting a sleeping bag with an appropriate temperature rating and insulation type is crucial to ensure safety and comfort during cold weather camping.”
Additional Accessories for Extreme Cold Protection
In extreme cold environments, supplementary accessories can significantly enhance insulation and prevent frostbite or hypothermia. Properly equipped hands, face, and extremities are essential for overall safety.
- Hand Warmers: Disposable or rechargeable packs generate heat and can be inserted into gloves or pockets to keep extremities warm.
- Thermal Gloves: Insulated, windproof gloves made from waterproof materials, often with fleece linings, retain warmth while allowing dexterity.
- Face Masks and Balaclavas: Designed to cover the face and neck, these protect against wind chill and frostbite, especially during high-wind or snowstorm conditions.
Planning and Safety Considerations for Winter Camping

Engaging in winter camping demands meticulous planning and a proactive approach to safety, given the unique challenges posed by cold weather environments. Proper preparation not only enhances the outdoor experience but is crucial in preventing emergencies and ensuring a safe, enjoyable trip. Focusing on accurate weather forecasting, thoughtful route planning, and comprehensive emergency preparedness forms the foundation for successful winter camping adventures.
Understanding and assessing the environment before and during your trip enable campers to identify potential hazards, adapt plans accordingly, and respond effectively to unexpected situations. This section emphasizes the importance of detailed planning in cold weather conditions, highlighting key safety measures, tools, and practices that contribute to a secure camping experience in winter landscapes.
Weather Forecasting and Route Planning
Accurate weather information is vital for winter camping to anticipate conditions such as snowstorms, temperature drops, and wind chill factors that can significantly impact safety and comfort. Utilizing reliable weather services, such as national meteorological agencies and specialized winter weather apps, allows campers to monitor forecasts in real-time. Planning routes that avoid high-risk areas, such as avalanche-prone slopes or unstable snowfields, minimizes exposure to dangerous environments.
When mapping out your itinerary, account for potential daylight limitations and ensure that your route includes feasible bailout points or shelters. Incorporating alternative plans to adapt to changing weather conditions helps in maintaining safety throughout the trip. It is advisable to inform a trusted contact or local authorities about your planned route and expected return time as a precautionary measure.
Campsite Safety Assessment
Evaluating the suitability and safety of your campsite is essential, especially when snow and ice are involved. Inspect snow conditions thoroughly, checking for signs of instability such as recent avalanches, cracks, or uneven snow surfaces that could indicate hidden hazards. Avoid setting up camp directly beneath overhanging snow or ice, which may pose risks of collapse or avalanche during temperature fluctuations.
Assess the ground for firm, level surfaces that can support your tent and gear. Consider the proximity to water sources, ensuring they are not likely to flood or freeze solid. Look out for potential hazards such as sharp rocks, tree branches, or unstable snowbanks. Regularly monitor weather updates and snow conditions during your stay to adapt your campsite arrangement if necessary.
Safety Items Checklist
Equipping yourself with essential safety items is critical in cold weather camping. These tools and supplies enable prompt response to emergencies and improve overall safety in harsh environments. The following checklist provides a comprehensive overview of vital safety gear:
- First aid kit with supplies suitable for cold injuries, including frostbite and hypothermia treatment items.
- Navigation tools such as detailed topographic maps, a compass, and a GPS device.
- Reliable communication devices, including a fully charged satellite phone, two-way radios, or personal locator beacons (PLBs).
- Extra warm clothing, thermal blankets, and emergency shelter options like bivvies or emergency tents.
- Fire-starting tools, including waterproof matches, lighters, and fire starters, stored in waterproof containers.
- Multitools or sturdy knives for various survival needs.
Preparing these safety items beforehand ensures readiness for unforeseen circumstances, such as getting lost, injuries, or sudden weather changes. Regularly check the functionality of communication devices and ensure batteries are protected from cold temperatures to prevent failures when most needed.
Safety Measures and Emergency Response Table
| Emergency Situation | Recommended Safety Measure | Response Procedure |
|---|---|---|
| Frostbite or Hypothermia | Move affected person to a warmer environment and remove wet clothing | Provide insulated blankets, apply warm packs to core areas, and seek medical assistance immediately |
| Getting Lost or Disoriented | Use navigation tools to determine location and mark position | Follow established trail or return to known landmarks, and inform someone of your location |
| Snow Collapse or Avalanche | Avoid slopes with recent avalanche activity and unstable snow | Move laterally to safer terrain, and if caught in an avalanche, attempt to stay on the surface and create an air pocket if possible |
| Fire or Equipment Failure | Maintain a backup fire-starting kit and spare batteries for devices | Use alternative fire-starting methods and implement emergency shelter protocols if necessary |
| Severe Weather or Windstorm | Seek shelter in a designated safe area or established shelter | Secure all loose gear, avoid camping under overhangs, and stay inside until conditions improve |
Techniques for Staying Warm and Conserving Energy

Maintaining body warmth and managing energy levels are crucial aspects of winter camping, especially in cold environments where exposure can lead to health risks such as hypothermia and frostbite. Employing effective techniques to stay warm ensures safety, comfort, and the ability to enjoy outdoor activities despite low temperatures.A combination of proper layering, physical activity, hydration, and strategic use of heat sources can significantly enhance your thermal regulation.
Understanding how to conserve energy allows you to extend your stamina and avoid unnecessary fatigue, which can impair judgment and increase vulnerability to cold-related conditions.
Proper Layering and Clothing Management
Effective insulation starts with the right clothing system. The three-layer approach—base layer, insulation layer, and outer shell—maximizes warmth while allowing moisture to escape. The base layer should be moisture-wicking to keep sweat away from the skin, preventing dampness that accelerates heat loss. The insulation layer traps body heat, with materials such as fleece or down being ideal. The outer shell provides protection against wind, snow, and rain, and should be breathable to prevent internal condensation.
- Regularly adjust layers based on activity level and weather conditions.
- Avoid overdressing, which can lead to sweating and subsequent cooling.
- Use windproof and waterproof outer shells to block cold air and moisture ingress.
Active Movement and Hydration
Physical activity generates body heat and prevents chilling. Incorporate gentle movement—such as walking or stretching—periodically to boost circulation. However, avoid excessive exertion that causes sweating, as moisture increases heat loss once activity ceases.Proper hydration is vital, as cold environments can suppress thirst signals while dehydration impairs circulation and thermoregulation. Drinking warm fluids helps maintain core temperature and supports metabolic processes that generate heat.
- Consume warm beverages frequently, avoiding alcohol and caffeine, which can impair thermoregulation.
- Incorporate light, nutritious snacks high in calories and fats to sustain energy levels.
- Maintain steady hydration to support blood flow and prevent dehydration-related cold susceptibility.
Using Heat Packs and Managing Body Temperature
Chemical heat packs or electric heating pads can provide targeted warmth to critical areas such as the hands, feet, and torso. Applying heat packs during rest periods or sleep can help prevent cold-related injuries.When managing body temperature during sleep, use insulated sleeping pads and appropriate sleeping bags rated for low temperatures. Wear thermal underwear and insulated hats to conserve heat, as a significant amount of body heat can be lost through the head and extremities.
- Place heat packs on major blood vessels near the neck, wrists, and ankles for maximum heat transfer.
- Use insulated, moisture-wicking sleeping layers and keep dry to prevent heat loss.
- Avoid overheating during activity, which can lead to excessive sweating and subsequent cooling.
Conserving Energy and Preventing Cold-Related Illnesses
Conservation of energy involves pacing activities and optimizing nutrition to prevent fatigue and maintain warmth. Overexertion can lead to sweating, dehydration, and rapid heat loss once activity stops, increasing the risk of hypothermia.Adopt a steady, moderate pace during physical tasks and rest frequently to replenish energy. Focus on high-calorie, nutrient-dense foods to compensate for increased metabolic demands in cold weather.
Prioritize foods rich in fats and carbohydrates, which provide sustained energy release.To prevent frostbite and hypothermia, adhere to these practical tips:
- Wear layered, insulated clothing and cover all exposed skin areas, especially extremities and face.
- Keep moving to promote circulation, but avoid excessive sweating; adjust clothing as needed.
- Use hand and foot warmers during rest periods and at night.
- Stay dry by changing out of wet clothing immediately and avoiding snow or moisture contact.
- Seek shelter promptly at signs of prolonged cold exposure or numbness.
- Monitor body temperature regularly, noting sensations of cold, numbness, or shivering, which are early signs of hypothermia or frostbite.
- Maintain a well-balanced diet and hydration to support body heat production and energy levels.
Food and hydration strategies in cold weather

Proper nutrition and hydration are vital components of a successful winter camping experience. Cold weather increases energy expenditure and the risk of dehydration, making strategic planning essential for maintaining warmth, stamina, and overall health during outdoor adventures in low temperatures. Ensuring access to high-calorie foods and safe water sources can significantly influence your comfort and safety throughout the trip.Effective food and hydration practices in cold climates focus on maximizing caloric intake while minimizing weight and bulk.
High-energy, nutrient-dense meals help sustain body heat and combat fatigue, while proper water management prevents dehydration and ensures proper bodily functions despite the freezing environment.
High-calorie, easily prepared meals for winter camping
In cold weather, your body burns more calories to maintain core temperature, necessitating meals rich in energy and nutrients that are easy to prepare in challenging conditions. Focus on foods that offer a high caloric density with minimal cooking time, such as dehydrated or freeze-dried meals, hearty soups, and energy bars.Common options include instant oatmeal supplemented with nuts and dried fruits, dehydrated soups combined with powdered protein, and lightweight, pre-cooked grains like instant rice or couscous.
Adding calorie-dense fats, such as cheese or oil, enhances energy content and flavor. Pre-packaged camping meals designed for cold environments often contain a balanced mix of carbohydrates, proteins, and fats, providing sustained energy release over extended periods.
Melting snow effectively and safely for water supply
Access to reliable water sources is critical during winter camping, especially in snow-covered regions where liquid water may be scarce. Melting snow is a practical solution but requires proper techniques to ensure safety and efficiency.First, it is essential to collect clean, fresh snow, avoiding any that appears discolored, dirty, or contaminated by debris. Using a portable stove or fire, slowly melt the snow in a pot or container, stirring regularly to facilitate even melting.
It is advisable to filter or treat the water post-melting to eliminate potential pathogens or impurities, especially in areas where wildlife or human activity may have contaminated the snow.To maximize efficiency, fill your container with snow and gradually add small amounts of water as it melts, reducing the risk of overboiling or splattering. Remember to bring sufficient fuel for melting snow, as it can be energy-intensive, and always prioritize safety by ensuring your stove is stable and well-ventilated during the process.
Portable cooking devices suitable for cold climates
The choice of cooking equipment significantly impacts your ability to prepare meals efficiently in winter conditions. Below is a comparison table of popular portable cooking devices suitable for cold weather camping, considering factors such as fuel efficiency, ease of use, and performance in low temperatures:
| Device | Fuel Type | Advantages | Disadvantages |
|---|---|---|---|
| Canister Stove | Isobutane/propane mix | Lightweight, easy to ignite, reliable in cold weather with proper canisters | Less effective below -10°C unless specially designed, can be costly |
| Liquid Fuel Stove | White gas, kerosene, unleaded gasoline | Excellent performance in extreme cold, high heat output | Heavier, requires more maintenance, potentially hazardous |
| Multi-fuel Stove | Various (white gas, kerosene, diesel) | Versatile, reliable in different conditions | More complex operation, heavier equipment |
| Alcohol Stove | Denatured alcohol or ethanol | Simple, lightweight, inexpensive | Lower heat output, slow boiling times, less effective in extreme cold |
Lightweight, nutrient-dense snacks and beverages for cold weather
In cold environments, quick and portable snacks are vital for maintaining energy levels between meals. Nutrient-dense options provide essential calories with minimal bulk, helping to sustain warmth and stamina during strenuous activities.Examples include energy bars packed with nuts, seeds, and dried fruits, which offer a balanced mix of fats, carbohydrates, and protein. Jerky made from beef, turkey, or plant-based alternatives provides a portable source of protein and salt to replenish electrolytes lost through sweating.
Nut butters (peanut, almond, or other varieties) can be spread on crackers or eaten directly, providing concentrated calories and healthy fats.For beverages, instant hot chocolate mixes, electrolyte drinks, or powdered soups serve as warming, hydrating options. Incorporating high-calorie, warm drinks not only sustains energy but also helps combat the chill by raising core body temperature.
Lightweight, nutrient-dense snacks such as trail mix, energy bars, and jerky are essential for maintaining caloric intake in winter conditions, especially during active periods and when access to cooking facilities is limited.
Setting up and maintaining a campsite in cold conditions

Camping in cold weather requires careful planning and precise execution to ensure safety, warmth, and comfort throughout the stay. Selecting an optimal site, establishing a secure tent setup, and creating protective barriers are fundamental steps that significantly influence the overall experience and safety in winter camping environments. Properly setting up your campsite minimizes exposure to wind and snow while maximizing insulation and safety for all occupants.When camping in freezing conditions, the environment demands a strategic approach to site selection and tent setup.
The goal is to create a sheltered area that protects from wind chill, prevents snow accumulation, and maintains a stable, insulated environment. This involves assessing the terrain, prevailing wind directions, and snow conditions to determine the best location for establishing your base.
Choosing an optimal campsite with protection from wind and snow
In cold weather, the selection of a campsite is crucial for safety and comfort. The ideal site should be located on slightly elevated ground to prevent snowdrift buildup and avoid depressions where cold air tends to settle. It must be shielded from prevailing winds, which can significantly decrease perceived temperature and increase heat loss. Begin by scouting an area that offers natural windbreaks such as dense tree lines, ridges, or large rock formations.
These features help reduce wind velocity around the campsite. Avoid areas prone to avalanches or snow slides, especially on slopes or unstable snowfields. Snow accumulation should be minimal and stable, with a firm, frozen ground beneath the snow layer providing a solid base for tent anchoring.Once a suitable site is identified, clear loose snow from the immediate area around the tent site to create a flat, stable platform.
Use snow shovels or skis to remove excess snow and level the ground where possible, maximizing comfort and stability.
Pitching tents on snow or frozen ground, including anchoring techniques
Setting up a tent on snow or frozen terrain requires specialized techniques to ensure stability and safety. Unlike regular grounds, snow and ice demand secure anchoring methods to withstand wind and shifting conditions.Start by selecting a tent with sturdy, reinforced stakes or pegs designed for winter conditions. If such stakes are unavailable, use alternative anchors such as snow stakes, driftwood, or large rocks.
For snow, drive stakes at a 45-degree angle into the snowbank, or bury them horizontally in the snow and secure with additional snow or ice blocks to prevent pulling out under tension.In cases where stakes cannot be driven into the ground, use deadman anchors: bury a weighted object such as a large snowball or a pack filled with gear connected to the tent lines with durable cord.
Make sure the anchoring points are well embedded and that tension is evenly distributed to prevent the tent from collapsing or shifting.During installation, ensure the tent’s guy lines are taut and anchored securely. Use snow or ice axes to carve footholds or anchors into the terrain if necessary, and periodically check tension levels during the stay to accommodate snow settling or wind changes.
Insulating tents and sleeping areas to retain heat
Effective insulation is critical for maintaining warmth inside the tent and sleeping areas. It involves both structural modifications and strategic layering to prevent heat loss.Start by selecting a tent with a full-coverage rainfly and a double-wall construction to reduce heat transfer. Inside, lay insulating mats such as closed-cell foam pads or inflatable sleeping pads topped with sleeping bags rated for sub-zero temperatures.
Elevate sleeping areas above the snow or cold ground to minimize conductive heat loss.Enhance insulation by creating a barrier between the tent floor and the cold surface. Use a thick layer of insulating material like foam mats, foam sheeting, or even layers of dry snow compacted under the sleeping area—known as a snow trench—ensuring it is stable and dry. To further insulate the tent interior, hang thermal blankets or reflective insulations on the walls, or line the tent with additional insulating layers.
For sleeping bags, choose models with high fill power and proper temperature ratings, and consider using bivvy bags or liners for added warmth.
Creating windbreaks and snow barriers for campsite safety
Windbreaks and snow barriers are vital for reducing wind chill and preventing snow from accumulating inside the campsite. Constructing these barriers strategically around the tent area enhances safety and comfort.Begin by assessing the prevailing wind direction and positioning barriers perpendicular to it. Use natural features such as rocks, fallen logs, or densely packed snowbanks to create initial windbreaks. Additional human-made barriers can be constructed from snow blocks, logs, or packed snow walls.
When building snow walls, carve blocks from a snowbank and pile them in a staggered manner to form a solid, stable barrier. Pack the snow firmly to prevent crumbling.For increased effectiveness, position snow barriers downwind from the tent, with a slight angle to redirect wind flow away from the shelter. Combine multiple barriers if necessary for enhanced protection. When constructing windbreaks, ensure they are sufficiently high and wide to block wind and snow drift, but do not obstruct airflow entirely, as proper ventilation remains essential.Regular maintenance of these barriers is necessary, especially after heavy snow or wind events.
Clear accumulated snow from barriers’ surfaces to maintain stability and durability, and reinforce structures as needed to sustain protection throughout your stay.
Leave No Trace and Environmental Considerations in Winter Camping
Winter camping offers a unique opportunity to immerse oneself in pristine snowy landscapes, but it also requires heightened awareness of environmental stewardship. Protecting these fragile ecosystems ensures that future generations can enjoy the same natural beauty. Practicing responsible camping in snow-covered terrains minimizes your ecological footprint, preserves wildlife habitats, and maintains the area’s natural integrity.In cold weather environments, special care must be taken to prevent disturbances to wildlife, avoid damaging vegetation, and leave the landscape as untouched as possible.
Snow and ice can mask signs of human activity, making it essential for campers to adopt strict Leave No Trace principles tailored to winter conditions. Proper planning, packing out all waste, and respecting wildlife are fundamental to sustainable winter camping.
Specific Practices for Minimizing Environmental Impact in Snow-Covered Terrains
In snow-covered environments, minimizing impact involves unique considerations. The snow can conceal tracks, plant life, and delicate soil layers, so campers must be cautious to avoid disturbing the natural features. Establishing campsites on durable surfaces such as packed snow or existing clearings reduces the risk of creating new scars or damaging underlying vegetation. When selecting a site, avoid areas near water sources or animal trails to prevent interference with wildlife or pollution of water bodies.Walking and moving around should be done with mindfulness to avoid creating multiple pathways that can disturb the snowpack and underlying terrain.
Use existing trails wherever possible, and minimize trampling of vegetation or mosses that may be present beneath the snow. When snow is deep, use snowshoes to distribute weight evenly, reducing the risk of creating broad impact zones.
Procedures for Packing Out Waste and Respecting Wildlife
Effective waste management is critical in winter camping, where waste can be hidden under snow or frozen in place. Campers must carry out all trash, leftover food, and human waste, ensuring no trace remains. Waste should be stored in sealed, durable bags or containers to prevent animal intrusion and environmental contamination. When appropriate, use biodegradable or environmentally safe waste bags designed for winter conditions.Respect for wildlife involves maintaining a safe and non-intrusive distance.
Avoid approaching animals, especially during winter when they are conserving energy or foraging for limited resources. Refrain from leaving food scraps or scented items that could attract animals to campsites, which might lead to dependency or dangerous interactions. Observing animals from afar and minimizing noise ensures their natural behaviors remain undisturbed.
Eco-Friendly Practices Tailored to Winter Camping Settings
- Pack out all waste, including human waste, using designated biodegradable waste bags or container systems designed for freezing conditions.
- Use established trails and campsites to minimize the creation of new impact points.
- Avoid breaking or damaging ice formations or snow structures that serve as habitats for wildlife or natural features.
- Opt for biodegradable soaps and cleaning products, and use minimal water to reduce environmental disturbance.
- Minimize campfire use; when necessary, ensure fires are constructed safely and completely extinguished, avoiding damage to snow or ice.
- Respect wildlife by observing from a distance, avoiding feeding animals, and not disturbing their natural winter behaviors.
- Follow local regulations and guidelines for winter camping, including restrictions on campfire locations and waste disposal procedures.
Summary of Best Practices for Sustainable Camping in Cold Environments
| Practice | Description |
|---|---|
| Site Selection | Choose durable and existing campsite locations that minimize impact on snow and underlying vegetation. |
| Waste Management | Carry out all waste, including human waste, in sealed containers, and dispose of it properly away from water sources. |
| Wildlife Respect | Maintain distance from animals, avoid feeding, and keep noise levels low to prevent disturbance. |
| Impact Minimization | Use snowshoes, stay on established trails, and avoid breaking ice formations or damaging natural features. |
| Fire and Cooking | Limit fire use, ensure extinguishment, and prefer insulated stoves that reduce environmental impact. |
| Leave No Trace Principles | Follow outdoor ethics by planning ahead, minimizing campfire impacts, respecting wildlife, and leaving what you find. |
Ending Remarks
In conclusion, proper preparation for cold weather camping combines the right equipment, safety protocols, and environmental mindfulness. With thoughtful planning and attention to detail, you can embrace winter adventures confidently and responsibly, creating lasting memories amidst the beauty of nature.