Water in the Atmosphere Water in the Atmosphere

Water in the Atmosphere

Water in the Atmosphere • The Water Cycle

Humidity • Humidity is a measure of the amount of water vapor in the air. • The amount of water vapor that the air can hold depends on its temperature. • Warm air can hold more water vapor than cool air.

Humidity • The percentage of water vapor in the air compared to the maximum amount the air could hold is called the relative humidity.

• Relative humidity can be measured using a psychrometer.

Water in the Air • Clouds form when water vapor in the air becomes liquid water or ice crystals. • The process by which molecules of water vapor in the air become liquid water is called condensation.

Water in the Air • The temperature at which condensation begins is called the dew point. • Clouds form whenever air is cooled to its dew point and particles are present.

Types of Clouds • Meteorologists classify clouds into three main types (shapes): – 1. Cumulus – 2. Stratus – 3. Cirrus • Clouds are also classified by their altitude. • Each type of cloud is associated with a different type of weather.

Cumulus • Clouds that look like fluffy, rounded piles of cotton are called cumulus clouds. • Cumulus clouds usually indicate fair weather. • Towering clouds with flat tops, called cumulonimbus clouds, often produce thunderstorms.

Stratus • Clouds that form in flat layers are called stratus clouds. • As stratus clouds thicken, they may produce drizzle, rain, or snow. • They are then called nimbostratus clouds.

Cirrus • Wispy, feathery clouds are called cirrus clouds. • Cirrus clouds form only at high levels, where temperatures are very low. • As a result, cirrus clouds are made of ice crystals. • Cirrocumulus clouds often indicate that a storm is on its way.

Lenticular Clouds • Air gets pushed upward where it cools and condenses into clouds. • Depending on how smooth the flow is, you can get some amazing clouds formations

Mammatus Clouds

• Clouds that form at or near the ground are called fog • Fog often forms when the ground cools at night after a warm, humid day