علم المحيطات - محاضرات

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Questions and Answers

ما هو تعريف الأمواج ببساطة؟

عبارة عن تموجات سطحية تنتج بسبب هبوب الرياح فوق المسطحات المائية

ما اسم الأمواج التي لا علاقة لها بالرياح؟

أّواج تسونامي أو أمواج المد

ما هو العامل الرئيسي في تكون أمواج البحر؟

تأثير فعل الرياح

ما هي سرعة الأمواج في المتوسط؟

3 كم / ساعة Signup and view all the answers

من هو صاحب أول نظرية عملية لتفسير ظاهرة الحركة الاهتزازية للأشياء الطافية؟

فرانز جيرزنر Signup and view all the answers

ما هي العوامل التي تُساهم في نشأة الأمواج؟

سرعة الرياح Signup and view all the answers

قوم بمطابقة عناصر الأمواج مع تعريفها

ارتفاع الموجة = طول ارتفاع الموجة من قمة الحوض إلى ذروتها طول الموجة = المسافة الأفقية بين قمتين لموجتين متجاورتين زمن دورة الموجة = الزمن الذي تستغرقه الموجة المتعاقبة في دورانها اتجاه انتشار الموجة = اتجاه حركة الموجة Signup and view all the answers

ما هي أشد الأمواج ارتفاعًا؟

الأمواج التي تقع في البحار الجنوبية بين دائرتي عرض 40 درجة جنوبًا وسواحل أنتاركتيكا Signup and view all the answers

ما هو الهدف الأساسي من دراسة التفاعل مابين الرياح والأمواج؟

لخدمة الأغراض الحربية Signup and view all the answers

ما هو الهدف الرئيسي من دراسة الأمواج؟

لفهم خصائص الأمواج و كيفية نشأتها و كيف تؤثر على مختلف الظواهر الجغرافية Signup and view all the answers

ما هي أنواع الأمواج التي تصنف بناء على سرعة انتشارها؟

أّواج سريعة Signup and view all the answers

هل تُعتبر الأمواج الهادئة هي الأُخرى من نوع الأمواج المتكسرة؟

False Signup and view all the answers

ما هي العوامل التي تُؤثر في سرعة أمواج البحر؟

مياه المحيط في حركة مستمرة وحركة الموجة و عمق المياه Signup and view all the answers

Study Notes

Oceanography - Lecture Notes

The course is about the geography of seas and oceans
The lecturer is Dr. Ibrahim Said Saber Bakri
He teaches Physical Geography and Geomorphology
The department is Geography, Faculty of Girls, Ain Shams University

Lecture Objectives

Students will be able to describe the movement of sea and ocean water
Students will understand the nature of waves
They will grasp the factors causing waves
They will analyze wave characteristics
They will comprehend wave energy
Students will be able to categorize waves
They will understand the relationship between wind and waves
They will grasp how wind energy moves to waves
They will learn the factors influencing wave speed
They will understand modifications of waves in shallow coastal waters
They will learn measurement methods of waves, tides, and ocean currents
The last topic will cover Tsunami waves

Waves - Detailed Study

Waves are surface undulations caused by wind. Other wave types are generated by earthquakes, landslides (like tsunamis), and astronomical forces.
Studying wave characteristics like intensity, variations in size, and measurement difficulties; especially during intense storms remain incomplete.
Scientists have developed specialized tools and techniques to study various aspects and behaviors.
Water particles move in circular paths when a wave passes.
Waves exhibit a particular motion in deep water, transforming into elliptical orbits in shallow water.
Wave tanks and experiments like those conducted by Ernst and Gerzner (1815) provided insights into wave characteristics, notably the conservation of energy and water particle movement.
Wave height, length, and period are crucial elements that form the wave.
Factors influencing wave formation: wind speed, duration, fetch (the area over which the wind blows).
The interaction between wind and waves is a complex relationship; wind energy moves into waves over varying distances.
Wave characteristics vary depending on the depth of water, proximity to land, and the presence of obstacles.
Instruments like wave recorders and radar help measure relevant data in wave analysis.
The role of computers in analyzing wave data is significant.

Waves - Wave Formation

Wave formation is a result of wind action on sea surfaces. The wind's interaction causes ripples, which progress into waves.
Wind's pressure and friction disturb the water's equilibrium, transferring energy from the atmosphere.
Wind-driven waves, often referred to as surface waves, have different characteristics based on wind strength and duration.
The various components involved in the formation of waves, like speed, distance, and length, were considered in the discussion.
The distance over which wind continues to blow, known as fetch, plays a critical role.

Wave Elements

Wave height (vertical distance from trough to crest)
Wave length (horizontal distance between two successive crests or troughs)
Wave period (time taken for two successive crests to pass a fixed point)
Wave propagation direction

Wave Characteristics

Mean wave height in oceans ranges from 5–15 ft (1.5–4.6 m), occasionally reaching 40–50 ft (12–15 m) during storms.
Wave lengths (horizontal dimension) range from 200–700 ft (60–210 m).
Wave speed usually falls within the range of 20–60 mph (32–96 km/h).
The interplay of various factors like wind velocity, duration, and water depth creates intricate wave patterns.

Wave Classification

Waves are categorized based on their speed, ranging from fast (40-60 mph) to slow (0-20 mph), and whether they are in deep or shallow water.
Different types of waves (deep-water or shallow-water), depending on water depth relative to wave length, are described.

Relation Between Wind and Waves

Wind's effect on waves starts subtly with ripples ("ripples").
Ripples grow into more significant waves as wind strength and duration increase.
Water movement is rotational in waves.

Energy Transfer from Wind to Waves

The process of energy transfer from wind to waves is complicated.
The factors influencing this process (strength and duration of wind, water conditions, and water surface area) were described in the lecture.
Waves are ultimately driven by wind.
Wind's strength and duration significantly impact generated waves. The broader the area the wind affects, the larger the waves will be.

Factors Affecting Wave Speed

The wave's speed depends on water depth and wave length.
Short waves are faster in shallower waters compared to deep water. In deep water, wave speed is related to the wave length.

Wave Changes in Shallow Water

Waves undergo changes when entering shallow water.
Waves reverse direction, bounce back, and break as they encounter shallow nearshore waters.
Factors like the angle of the water, depth variations, and coastal features influence the changes seen in wave motion.

Measuring Waves, Tides, and Currents

Methods of measuring waves, tides, and currents were explored.
The methodologies include floatation devices, vertical measuring instruments, and current-measuring buoys.
Instruments like wave-measuring devices are used in modern practice.

Tsunami Waves

Tsunamis are powerful waves caused by seismic events (earthquakes, volcanic activity).
Tsunami waves are usually less prominent in deep water but gain extreme height in shallow coastal waters,.
The height of tsunami waves depends on coastal topography and water depth.
Tsunamis are most frequent and devastating in the Pacific Ocean region.

Conclusion

The lecture provided a comprehensive overview of ocean waves. This was a deep dive into oceanography, detailing various wave characteristics, types, formation processes, and the interactions between wind and waves.

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Description

تدور هذه المحاضرات حول جغرافيا البحار والمحيطات. سيتعلم الطلاب كيفية وصف حركة المياه في البحر والمحيط، وفهم طبيعة الأمواج وكيفية تصنيفها، بالإضافة إلى دراسة العلاقة بين الرياح والأمواج وتأثيرها على الطاقة الموجية.