1ºH: Weather, Climate, and Natural Landscapes
1. Weather vs. Climate
Weather is the condition of the atmosphere at a particular place and time. It includes things like temperature, rain, wind, clouds, and humidity. Weather changes quickly, sometimes from hour to hour or day to day. For example, if it is raining and windy today, that is the weather for today.
Climate is the average weather in a place over a long period, usually at least 30 years. Climate tells us what kind of weather is typical in a region. For example, saying that Spain has hot, dry summers and mild, rainy winters describes the climate.
- Example of weather: “It is snowing this morning in Madrid.”
- Example of climate: “Winters in Madrid are usually cold and dry.”
2. Elements and Factors of Climate
Main elements of climate:
- Temperature: How hot or cold the air is. Measured in degrees Celsius (°C). It changes with the time of day, season, latitude (distance from the Equator), altitude (height above sea level), and distance from the sea.
- Precipitation: Water that falls from the sky, such as rain, snow, sleet, or hail. Measured in millimeters (mm). Precipitation depends on humidity, temperature, altitude, and proximity to water bodies.
- Atmospheric Pressure: The weight of air pressing down on the Earth’s surface. Measured in hectopascals (hPa) or millibars (mb). High pressure usually means clear, sunny weather; low pressure means clouds and rain.
- Wind: Moving air caused by differences in atmospheric pressure. Wind moves from areas of high pressure to low pressure. Its speed is measured with an anemometer and its direction with a weather vane.
Factors that affect climate:
- Latitude: Areas near the Equator are warmer because the sun’s rays hit more directly. Areas near the poles are colder.
- Altitude: The higher you go, the colder it gets. For every 100 meters you go up, the temperature drops about 0.6°C.
- Distance from the sea: Places near the sea have milder temperatures and more rain. The sea warms up and cools down more slowly than land, so coastal areas have smaller temperature changes.
- Ocean currents and prevailing winds: Warm or cold ocean currents and winds can make a place warmer, colder, wetter, or drier.
3. The Atmosphere
The atmosphere is a layer of gases that surrounds the Earth. It is made mostly of nitrogen and oxygen. The atmosphere is essential for life because it provides oxygen, protects us from the Sun’s harmful rays, and keeps the planet warm enough for living things.
Layers of the atmosphere (from lowest to highest):
- Troposphere: Closest to the Earth’s surface. Contains most of the air and water vapor. Weather happens here.
- Stratosphere: Contains the ozone layer, which absorbs harmful ultraviolet (UV) rays from the Sun.
- Mesosphere: Very cold. Meteors burn up here.
- Thermosphere: Very hot. The International Space Station orbits here.
- Exosphere: The outermost layer, where satellites orbit.
Meteorology is the science that studies the atmosphere and weather. Meteorologists use instruments like thermometers (temperature), barometers (pressure), anemometers (wind speed), and rain gauges (precipitation) to collect data and make weather forecasts.
4. Water Cycle and Rivers
The water cycle is the continuous movement of water on, above, and below the surface of the Earth:
- Water evaporates from oceans, lakes, and rivers.
- Water vapor rises and cools, forming clouds (condensation).
- Water falls as precipitation (rain, snow, hail).
- Water returns to rivers and oceans, starting the cycle again.
- Etapa de evaporación → Evaporation stage
- Etapa de condensación → Condensation stage
- Etapa de precipitación → Precipitation stage
- Etapa de recolección → Collection stage
Rivers are important because they transport water from land to the sea, help shape the landscape, and are part of the water cycle.
Examples of important rivers:
- Nile (Africa):
- The Nile is the longest river in the world, stretching about 6,650 kilometers. It flows through northeastern Africa, passing through countries like Uganda, Sudan, and Egypt. The Nile is vital for life in Egypt and Sudan, providing water for drinking, farming, and transportation. Ancient Egyptian civilization depended on the Nile’s yearly floods to grow crops and survive.
- Amazon (South America):
- The Amazon is the world’s largest river by volume and the second longest, at about 6,400 kilometers. It flows from the Andes Mountains in Peru across Brazil to the Atlantic Ocean, crossing several countries. The Amazon runs through the world’s largest rainforest, supports thousands of animal and plant species, and carries about one-fifth of all the fresh water that flows into the world’s oceans.
- Yangtze (Asia):
- The Yangtze is the longest river in Asia and the third longest in the world, at about 6,300 kilometers. It flows entirely within China, from the Tibetan Plateau to the East China Sea near Shanghai. The Yangtze is very important for transportation, agriculture (especially rice), and electricity production thanks to the Three Gorges Dam. It is also home to many unique animal species.
- Mississippi (North America):
- The Mississippi River is about 6,275 kilometers long and flows from northern Minnesota in the United States to the Gulf of Mexico. It is a major transportation route and supports agriculture, industry, and many cities along its banks. The river and its tributaries form one of the world’s largest river systems, essential for the economy and environment of North America
| Río | Dónde nace | Países que atraviesa | Dónde desemboca |
|---|---|---|---|
| Amazonas | Nevado Mismi, Andes (Perú) | Perú, Colombia, Brasil | Océano Atlántico (Brasil) |
| Nilo | Río Kagera → Lago Victoria | Burundi, Ruanda, Tanzania, Uganda, Sudán del Sur, Sudán, Egipto | Mar Mediterráneo (Egipto) |
| Yangtsé | Glaciares del Tanggula Shan (Tíbet, China) | China | Mar de China Oriental |
| Misisipi | Lago Itasca (Minnesota, EE. UU.) | Estados Unidos (solo) | Golfo de México |
5. Clouds, Humidity, and Precipitation
Humidity is the amount of water vapor in the air. High humidity means the air feels moist; low humidity means it feels dry.
Precipitation is water that falls from clouds to the ground. It can be rain, snow, sleet, or hail.
How clouds form:
- Warm, moist air rises.
- As it rises, it cools and water vapor condenses into tiny droplets around dust particles, forming clouds.
Types of clouds:
- Cumulus: Fluffy, white clouds. Usually mean fair weather.
- Cumulonimbus: Tall, dark clouds. Bring thunderstorms and heavy rain.
- Cirrus: Thin, wispy clouds high in the sky. Often signal a change in the weather.
6. Atmospheric Pressure and Wind
Atmospheric pressure is the weight of air on the Earth’s surface. It is higher at sea level and lower at high altitudes. High pressure brings clear, calm weather; low pressure brings clouds and rain.
Wind is moving air. It blows from high-pressure areas to low-pressure areas.
- Sea breezes: During the day, land heats up faster than the sea. Warm air rises over the land, and cooler air from the sea moves in to replace it, creating a breeze from the sea to the land.
- Monsoons and trade winds: Some winds are seasonal or constant and affect the climate of large regions.
7. Climate Zones and Types
The Earth is divided into different climate zones based on latitude and temperature:
- Hot (Tropical) Zone: Near the Equator. Always hot, with little variation. Includes equatorial, tropical, and desert climates.
- Temperate Zones: Between the tropics and polar circles. Four seasons, with moderate temperatures. Includes Mediterranean, oceanic, and continental climates.
- Cold (Polar) Zones: Near the poles. Very cold, with little precipitation. Includes polar and high mountain climates.
Examples:
- Equatorial climate: Hot and rainy all year. Dense rainforests.
- Desert climate: Hot and dry, with very little rain. Sparse vegetation.
- Mediterranean climate: Mild, wet winters and hot, dry summers. Found in southern Europe and parts of California.
- Polar climate: Extremely cold, with ice and snow all year.
8. Natural Landscapes
Natural landscapes are shaped by climate, water, soil, and living things. The main types are:
- Forests: Found in areas with lots of rain (equatorial, tropical, and temperate zones).
- Deserts: Very dry, little vegetation (hot and cold deserts).
- Grasslands: Wide open areas with grasses, found in temperate and tropical zones.
- Mountains: High areas with colder temperatures, found in many climate zones.
Spain is mostly in the temperate zone, with Mediterranean landscapes (forests, scrubland), some oceanic areas (green, rainy), and semi-arid or dry areas in the southeast.
9. Air Pollution and Climate Change
Air pollution is caused by human activities like burning fossil fuels, industry, and deforestation. It leads to:
- Acid rain: Damages plants, soils, and water bodies.
- Smog: A mix of smoke and fog, common in cities, harmful to health.
- Ozone layer destruction: Caused by chemicals (CFCs), lets more harmful UV rays reach Earth.
Greenhouse effect: Some gases (CO₂, methane) trap heat in the atmosphere, keeping Earth warm. Human activities are increasing these gases, causing global warming.
Climate change is the result of global warming. It causes:
- Melting ice caps and rising sea levels.
- More extreme weather: droughts, floods, hurricanes.
- Loss of habitats and species.
- Climate migration: people forced to leave their homes due to droughts or floods.
10. Environmental Awareness and Action
- Everyone can help fight climate change by saving energy, reducing waste, recycling, using public transport, and planting trees.
- International agreements like the Paris Agreement aim to reduce greenhouse gas emissions and protect the planet.
