Weather: Key Concepts

• Weather is the condition of the Earth's atmosphere at a specific time and place, in terms of appearance and temperature.

Key Weather Concepts

• Atmospheric pressure is the force exerted by the air within the Earth's atmosphere.
• Humidity is the measure of water vapor present in the atmosphere.
• Dew point is the temperature at which water vapor condenses into liquid droplets.
• Weather forecasting involves predicting future weather conditions through ongoing observations of atmospheric conditions.
• Air mass is a large volume of air characterized by uniform temperature, humidity, and pressure.
• Radio detecting and ranging (RADAR) is a remote sensing technology that analyzes radio waves reflected off objects in the atmosphere to measure weather data.
• Thermal radiation occurs when particles emit energy in the form of electromagnetic waves.
• A front is a boundary that forms when two different air masses meet.
• A high-pressure area is a region where air exerts greater pressure on the surface below.
• A short-range weather forecast predicts weather conditions for up to 48 hours.
• Heat capacity is a substance's ability to absorb or release energy.
• A long-range forecast predicts weather conditions over a period of 3 to 7 days.
• A phase change material can absorb and retain energy without changing its state.
• A low-pressure area is a region where rising air results in less dense air below.
• The Beaufort scale was used to estimate wind speed before the invention of anemometers.

6 Components of Weather

• Temperature
• Atmospheric pressure
• Cloud Formation
• Wind
• Humidity
• Rain

Instruments to Measure Weather, and Their Units

• Thermometer measures temperature in Fahrenheit (°F) or Celsius (°C).
• Hygrometer measures humidity in percentage (%).
• Rain gauge measures precipitation amount in millimeters (mm).
• Barometer measures atmospheric pressure in millibars.
• Wind vane measures wind direction (North, East, South, West).
• Anemometer measures wind speed in kilometers per hour (km/h) or miles per hour (m/h).

Albedo

• Albedo refers to how much light a surface reflects.
• High albedo example: snow
• Low albedo example: asphalt

Factors Affecting Atmospheric Pressure

• Temperature: Warmer air is less dense, leading to lower pressure, while colder air is denser, resulting in higher pressure.
• Altitude: Atmospheric pressure decreases with increasing altitude because there is less air above to exert pressure.
• Density of Air Molecules: More air molecules above a surface result in higher pressure due to increased force.

Hydrological Cycle

• Evaporation: Water turns into vapor and rises.
• Condensation: Water vapor cools and forms clouds.
• Precipitation: Clouds release water as rain, snow, or hail.
• Surface Water: Water flows through rivers into oceans.
• Groundwater: Some water infiltrates into the ground.

Weather Impact on Seasons

• Seasons are caused by the Earth's tilt.
• The hemisphere tilted toward the sun receives more direct sunlight, leading to warmer temperatures.
• The hemisphere tilted away from the sun receives less direct sunlight, leading to colder temperatures.

Solar Energy Distribution

• Radiation
• Convection

Pressure Systems

• Low-pressure systems draw air in, often associated with storms and precipitation.
• High-pressure systems have higher air pressure than their surroundings, often associated with clear, sunny skies.

Types of Fronts

• Cold Front: cold air mass displaces a warmer air mass.
• Warm Front: warm air mass displaces a colder air mass.
• Stationary Front: two air masses meet, but neither is strong enough to displace the other.
• Occluded Front: cold front overtakes a warm front.

Types of Severe Weather

• Tornado: a rotating column of air that touches the ground.
• Hurricanes: form over warm ocean waters, fueled by moisture and heat.
• Floods: an overflow of water onto normally dry land.

Water Heat Capacity

• Water has a high specific heat capacity.
• It takes a lot of energy to change the temperature of water.
• The high heat capacity of water helps regulate air temperature, making seasonal temperature changes gradual.

Importance of Weather Forecasting

• Allows people to prepare for severe weather events.
• Helps saves lives and protect property.

Humidity Impact on Temperature Sensation

• High humidity hinders the body's ability to cool down through sweating.
• When the air is already saturated with moisture, sweat evaporates more slowly, making it feel hotter.

Heat Transfer

• Convection: heat transfer within a fluid (air or water). Warm air rises, and cool air sinks.
• Radiation: heat transfer through electromagnetic waves. The sun heats the Earth's surface through radiation.
• Conduction: heat transfer through direct contact.

Breezes

• Land Breeze- the air above land cools and becomes very dense, leading to high pressure, the cooler air moves away from the land and towards the sea.
• Sea Breeze- the sun heats the surface layer over the land, resulting pressure causes the movement of low-level air from the sea to land.