Troposphere
The troposphere is the lowest layer of Earth's atmosphere, extending from the surface to approximately 8–9 km at the poles and 16–18 km at the equator, and containing about 80% of the atmosphere's total mass and virtually all of its water vapor and weather. Temperature generally decreases with altitude at the environmental lapse rate of approximately 6.5°C per 1,000 m (the standard atmosphere value), until reaching the tropopause, a temperature inversion that caps the troposphere. All significant weather phenomena — clouds, precipitation, thunderstorms, cyclones, and jet streams — occur within the troposphere, making it the most meteorologically active layer.
Key Formula
T(h) = T0 − L × h
LaTeX: T(h) = T_0 - L \cdot h
| Symbol | Meaning | Unit |
|---|---|---|
| T(h) | Temperature at altitude h | °C or K |
| T_0 | Temperature at sea level (standard: 15°C = 288.15 K) | K |
| L | Standard temperature lapse rate (6.5°C/1000 m = 0.0065 K/m) | K/m |
| h | Altitude above sea level | m |
Worked Example
Problem
An aircraft flies at an altitude of 10,000 m. Using the standard atmosphere lapse rate of 6.5°C per 1,000 m and a sea-level temperature of 15°C, calculate the expected temperature at that altitude.
Solution
Step 1: Apply the lapse rate formula. T(h) = T₀ − L × h T(10,000) = 15°C − (6.5°C/1000 m × 10,000 m) Step 2: Calculate the temperature drop. Temperature drop = 6.5 × 10 = 65°C Step 3: Calculate final temperature. T = 15 − 65 = −50°C
Answer
−50°C (223.15 K) at 10,000 m altitude
Troposphere Properties at Different Altitudes (Standard Atmosphere)
| Altitude (km) | Temperature (°C) | Pressure (kPa) | Air Density (kg/m³) | Notable Feature |
|---|---|---|---|---|
| 0 (sea level) | 15.0 | 101.3 | 1.225 | Surface conditions |
| 2 | 2.0 | 79.5 | 1.007 | Mountain tops region |
| 5 | −17.5 | 54.0 | 0.736 | Mid-troposphere |
| 8 | −37.0 | 35.7 | 0.526 | Polar tropopause level |
| 12 | −56.5 | 19.4 | 0.312 | Tropopause (mid-lat) |
| 18 | −56.5 | 7.5 | 0.122 | Tropical tropopause |
Interactive Tools
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Related Terms
Atmosphere (Earth)
The Earth's atmosphere is the layer of gases retained by Earth's gravity surrounding the planet, extending from the surface to approximately 10,000 km altitude where it gradually merges with the interplanetary medium. It consists primarily of nitrogen (78.09%), oxygen (20.95%), argon (0.93%), and carbon dioxide (0.04%), plus trace gases and variable amounts of water vapor. The atmosphere performs critical functions including regulating surface temperature through the greenhouse effect, protecting life from harmful ultraviolet radiation via the ozone layer, enabling weather and climate systems, and providing the oxygen and carbon dioxide essential for respiration and photosynthesis.
Stratosphere
The stratosphere is the second major layer of Earth's atmosphere, extending from the tropopause (approximately 12 km at mid-latitudes) to the stratopause at about 50 km altitude. Unlike the troposphere, temperature in the stratosphere increases with altitude — from about −56°C at the tropopause to approximately 0°C at the stratopause — due to the absorption of ultraviolet radiation by the ozone layer concentrated within it. This temperature inversion creates very stable conditions that suppress vertical mixing, making the stratosphere nearly cloud-free and home to the polar vortex and stratospheric jet streams; it is also the layer traversed by high-altitude commercial aircraft.
Weather
Weather refers to the short-term atmospheric conditions at a specific place and time, encompassing temperature, humidity, precipitation, wind speed and direction, cloud cover, and atmospheric pressure. It is driven by the uneven heating of Earth's surface by solar radiation, the rotation of the Earth (Coriolis effect), and the redistribution of energy and moisture by atmospheric circulation. Weather is distinct from climate, which describes the average patterns of weather over a region across 30 or more years; meteorologists predict weather using numerical weather prediction models, radiosonde data, satellite imagery, and surface observation networks.
From Greek "tropos" (a turn, turning) and "sphaira" (sphere). The prefix "tropo-" reflects the turbulent, mixing nature of this layer — the air constantly turns and churns. The term was introduced by French meteorologist Léon Philippe Teisserenc de Bort around 1900, who also identified the tropopause while investigating atmospheric temperature profiles using balloons.