Climate is the long-term pattern of weather in a region. It is what you expect over decades, not what happens on a given Tuesday. A desert has a dry climate. A rainforest has a wet one. Weather fluctuates daily. Climate shifts slowly, over years or centuries.

Scientists describe climate using averages and ranges. Temperature, rainfall, humidity, wind, and seasonality all matter. The data come from weather stations, satellites, ocean buoys, and ice cores. The record stretches back over a century in many places. Ice cores extend it hundreds of thousands of years.

Climate shapes everything: what crops grow, what houses are built, what clothes people wear. It determines where forests, grasslands, and deserts form. It influences culture and economy. When climate changes, these patterns shift. Some regions get wetter. Others dry out. Storms may intensify. The changes are uneven and hard to predict in detail.

Key factors

• Latitude and sunlight
• Ocean currents
• Atmospheric circulation
• Altitude and topography
• Greenhouse gas concentrations