- Climate and weather are fundamental to understanding how ecosystems are distributed across the Earth.
- Both describe atmospheric conditions but differ in timescale, variability, and application.
- Climate determines long-term environmental patterns that influence vegetation, animal life, and biome formation, while weather governs short-term fluctuations experienced in daily life.
Weather
Definition
Weather
Weather refers to the temporary state of the atmosphere in a specific place and time.
- Weather is the short-term state of the atmosphere, observed over hours or days.
- It reflects daily fluctuations driven by changing air masses, pressure systems, and local energy exchanges.
- Key weather variables:
- Temperature: How hot or cold the air is.
- Humidity: The amount of moisture in the air.
- Precipitation: Rain, snow, sleet, or hail.
- Wind Speed and Direction: How fast the wind is blowing and where it's coming from.
- Cloud Cover: The amount and type of clouds in the sky.
A tropical thunderstorm, a cold front, or a foggy morning are weather events lasting from minutes to several days.
| Feature | Weather | Climate |
|---|---|---|
| Timescale | Short-term (hours to days) | Long-term (≥30 years) |
| Scope | Localized and variable | Regional to global patterns |
| Variables | Temperature, humidity, wind speed, air pressure, cloud cover, precipitation | Average and extreme patterns of the same variables |
| Example | A thunderstorm occurring this evening | The monsoon pattern experienced every summer |
| Measured by | Weather stations and satellites recording daily data | Statistical analysis of long-term data sets |
Climate
Definition
Climate
Climate describes the average weather conditions in a region over a long period, typically 30 years or more.
- Describes long-term patterns and extremes of atmospheric conditions in a specific region.
- Measured over an average period of approximately 30 years (standard climatological baseline).
- Determined by global systems such as solar radiation, Earth’s tilt, ocean currents, and atmospheric circulation.
- It helps us understand what to expect in a given area, such as:
- Tropical Climates: Hot and humid, with heavy rainfall (e.g., the Amazon Rainforest).
- Arid Climates: Dry with minimal precipitation (e.g., the Sahara Desert).
- Temperate Climates: Moderate temperatures with distinct seasons (e.g., Western Europe).
The climate of a tropical rainforest is characterized by high temperatures ($26 - 28^\circ \text{C}$) and heavy rainfall ($2,000 - 5,000 \text{ mm}$ per year) with little seasonal variation.
Note- The World Meteorological Organization (WMO) uses 30-year intervals to calculate climate normals, most recently the period 1981–2010.
- New normals (1991–2020) reflect ongoing climate change trends.
The 30-Year Reference Period
- The 30-year averaging period was chosen to capture natural variability while minimizing the influence of short-term anomalies.
- Until 2020, the official climate baseline was 1981–2010.
- However, this approach has limitations:
- The database is too short to reflect century-scale variability.
- The 1981–2010 period includes rapid global warming, making it non-representative of long-term “normal” conditions.
